Category: Class 11

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Computer Science Guide Pdf Chapter 16 Inheritance Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Computer Science Solutions Chapter 16 Inheritance

11th Computer Science Guide Inheritance Text Book Questions and Answers

Part I

Choose The Correct Answer:

Question 1.
Which of the following is the process of creating new classes from an existing class?
a) Polymorphism
b) Inheritance
c) Encapsulation
d) superclass
Answer:
b) Inheritance

Question 2.
Which of the following derives a dass student from the base class school?
a) school: student
b) class student: public school
c) student: public school
d) class school: public student
Answer:
b) class student: public school

Question 3.
The type of inheritance that reflects the transitive nature is
a) Single Inheritance
b) Multiple Inheritance
c) Multilevel Inheritance
d) Hybrid Inheritance
Answer:
c) Multilevel Inheritance

Question 4.
Which visibility mode should be used when you want the features of the base class to be available to the derived class but not to the classes that are derived from the derived dass?
a) Private
b) Public
c) Protected
d) All of these
Answer:
a) Private

Question 5.
Inheritance is the process of creating new class from
a) Base class
b) abstract
c) derived class
d) Function
Answer:
a) Base class

Question 6.
A class is derived from a class which is a derived class itself, then this is referred to as
a) multiple inheritances
b) multilevel inheritance
c) single inheritance
d) double inheritance
Answer:
b) multilevel inheritance

Question 7.
Which amongst the following is executed in the order of inheritance?
a) Destructor
b) Member function
c) Constructor
d) Object
Answer:
b) Member function

Question 8.
Which of the following is true with respect to inheritance?
a) Private members of base class are inherited to the derived class with private
b) Private members of base class are not inherited to the derived class with private accessibility
c) Public members of base class are inherited but not visible to the derived class
d) Protected members of base class are inherited but not visible to the outside class
Answer:
b) Private members of base class are not inherited to the derived class with private accessibility

Question 9.
Based on the following dass decoration answer the questions (from 9.1 o 9.5 )

class vehicle
{
int wheels;
public:
void input_data(float,float);
void output_data();
protected:
int passenger;
};
class heavy_vehicle: protected vehicle
{
int diesel_petrol;
protected:
int load;
protected:
int load;
public:
void read_data(float,float)
void write_data(); };
class bus: private heavy_vehicle
{
char Ticket[20];
public:
void fetch_data(char);
void display_data(); >;
};

Question 9.1.
Which is the base class of the class heavy, vehicle?
a) Bus
b) heavy_vehicle
c) vehicle
d) both (a) and (c)
Answer:
c) vehicle

Question 9.2.
The data member that can be accessed from the function displaydata()
a) passenger
b) load
c) Ticket
d) All of these
Answer:
d) All of these

Question 9.3.
The member function that can be accessed by an objects of bus Class is
a) input_data()
b) read_data() ,output_data()write_data()
c) fetch_data(),display_data()
d) All of these
Answer:
c) fetch_data(),display_data()

Question 9.4.
The member function that is inherited as public by Class Bus
a) input_data()
b) read_data(),output_data(),write_data()
c) fetch_data(), display_data()
d) None of these
Answer:
d) None of these

Question 10.
class x
{
int a;
public :
x()
{}
};
class y
{
x x1;
public:
y()
{}
};
class z : public y,x
{
int b;
public:
z()
{}
}z1;

What is the order of constructor for object z to be invoked?
a) z,y,x,x
b) x,y,z,x
c) y,x,x,z
d) x,y,z
e) x,y,x,z
Answer:
e) x,y,x,z

Part – II

Very Short Answers

Question 1.
What is inheritance?
Answer:
Inheritance is one of the most important features of Object-Oriented Programming. In object-oriented programming, inheritance enables a new class and its objects to take on the properties of the existing classes.

Question 2.
What is a base class?
Answer:
The class to be inherited is called a base class or parent class.

Question 3.
Why derived class is called a power-packed class?
Answer:

• Multilevel Inheritance: In multilevel inheritance, the constructors will be executed in the order of inheritance.
• Multiple Inheritance: If there are multiple base classes, then it starts executing from the leftmost base class.

Question 4.
In what multilevel and multiple inheritances differ though both contains many base class?
Answer:
In case of multiple inheritance derived class have more than one base classes (More than one parent). But in multilevel inheritance derived class have only one base class (Only one parent).

Question 5.
What is the difference between public and private visibility mode?
Answer:
Private visibility mode:
When a base class is inherited with private visibility mode the public and protected members of the base class become ‘private’ members of the derived class.

Public visibility mode:
When a base class is inherited with public visibility mode, the protected members of the base class will be inherited as protected members of the derived class and the public members of the base class will be inherited as public members of the derived class.

Part – III

Short Answers

Question 1.
What are the points to be noted while deriving a new class?
Answer:

The following points should be observed for defining the derived class:

1. The keyword class has to be used.
2. The name of the derived class is to be given after the keyword class.
3. A single colon.
4. The type of derivation (the visibility mode), namely private, public or protected. If no visibility mode is specified, then by default the visibility mode is considered private.
5. The names of all base classes (parent classes) separated by a comma.

class derivedclass_name :visibility_mode
base_class_name
{
// members of derived class
};

Question 2.
What is differences between the members present in the private visibility mode and the members present in the public visibility mode?
Answer:
Private visibility mode:
When a base class is inherited with private visibility mode the public and protected members of the base class become ‘private’ members of the derived class.

Private visibility members can not be inherited further. So, it can not be directly accessed by its derived classes.
Public visibility mode:
When a base class is inherited with public visibility mode, the protected members of the base class will be inherited as protected members of the derived class and the public members of the base class will be inherited as public members of the derived class.

Public visibility members can be inherited by its child and can access in it.

Question 3.
What is the difference between polymorphism and inheritance though are used for the reusability of code?
Answer:
Polymorphism:

• Reusability of code is implemented through functions (or) methods.
• Polymorphism is the ability of a function to respond differently to different messages.
• Polymorphism is achieved through overloading.

Inheritance:

• Reusability of code is implemented through classes.
• Inheritance is the process of creating derived classes from the base class or classes.
• Inheritance is achieved by various types of inheritances namely single, multiple, multilevel, hybrid and hierarchical inheritances.

Question 4.
What do you mean by overriding?
Answer:
When a derived class member function has the same name as that of its base class member function, the derived class member function shadows/hides the base class’s inherited function. This situation is called function overriding and this can be resolved by giving the base class name followed by :: and the member function name.

Question 5.
Write some facts about the execution of constructors and destructors in inheritance.
Answer:

1. Base class constructors are executed first, before the derived class constructors execution.
2. Derived class cannot inherit the base class constructor but it can call the base class constructor by using Base_class name: :base_class_constructor() in the derived class definition
3. If there are multiple base classes, then it starts executing from the leftmost base class
4. In multilevel inheritance, the constructors will be executed in the order of inheritance The destructors are executed in the reverse order of inheritance.

IV. Explain In Brief (Five Marks)

Question 1.
Explain the different types of inheritance.
Answer:
Types of Inheritance;
There are different types of inheritance viz., Single Inheritance, Multiple inheritance, Multilevel inheritance, hybrid inheritance and hierarchical inheritance.

1. Single Inheritance:
When a derived class inherits only from one base class, it is known as single inheritance.

2. Multiple Inheritance;
When a derived class inherits from multiple base classes it is known as multiple inheritance.

3. Hierarchical inheritance:
When more than one derived classes are created from & single base class known as Hierarchical inheritance.

4. Multilevel Inheritance
The transitive nature of inheritance is itself reflected by this form of inheritance. When a class is derived from a class which is a derived class – then it is referred to as multilevel inheritance.

5. Hybrid inheritance:
When there is a combination of more than one type of inheritance, it is known as hybrid inheritance. Hence, it may be a combination of Multilevel and Multiple inheritances or Hierarchical and Multilevel inheritance or Hierarchical, Multilevel and Multiple inheritances.

Question 2.
Explain the different visibility modes through pictorial representation.
Answer:
Private visibility mode:
When a base class is inherited with private visibility mode the public and protected members of the base class become ‘private’ members of the derived class.

Protected visibility mode:
When a base class is inherited with protected visibility mode the protected and public members of the base class become ‘protected members’ of the derived class.

Public visibility mode:
When a base class is inherited with public visibility mode, the protected members of the base class will be inherited as protected members of the derived class and the public members of the base class will be inherited as public members of the derived class.

Question 3.
#include<iostream>
#include<string.h>
#include<stdio.h>
using name spacestd;
class publisher
{
char pname[15];
char hoffice[15];
char address[25];
double turnover;
protected:
char phone[3][10];
void register();
public:
publisher();
publisher();
void enter data();
void disp data();
};
class branch
{
char bcity[15];
char baddress[25];
protected:
int no_of_emp;
public:
char bphone[2][10];
branch();
~branch();
void havedata();
void givedata();
};
class author: public branch, publisher
{
int aut_code;
charaname[20];
float income;
public:
author();
~author();
void getdata();
void putdata();
};

Answer The Following Questions Based On The Above Given Program:

3.1. Which type of Inheritance is shown in the program?
3.2. Specify the visibility mode of base classes.
3.3 Give the sequence of Constructor/Destructor Invocation when object of class author is created.
3.4. Name the base class(/es) and derived class (/es).
3.5 Give number of bytes to be occupied by the object of the following class:
(a) publisher
(b) branch
(c) author
3.6. Write the names of data members accessible from the object of class author.
3.7. Write the names of all member functions accessible from the object of class author.
3.8 Write the names of all members accessible from member functions of class author.
Answer:
3.1 Multiple Inheritance
3.2 public
3.3 Constructors branch, publisher and author are executed.
Destructors author, publisher and branch will be executed.
3.4 Base classes : branch and publisher Derived class : author
3.5 a) publisher class object requires 93 bytes
b) branch class object requires 64 bytes
c) author class object requires 181 bytes

Question 4.
Consider the following C++ code and answer the questions.
class Personal
{
int Class, Rno;
char Section;
protected:
char Name[20];
public:
personal();
void pentry();
void Pdisplay();
};
class Marks:private Personal
{
float M{5};
protected:
char Grade[5];
public:
Marks();
void Mentry();
void Mdisplay();
};
class Result:public Marks
{
float Total,Agg;
public:
char FinalGrade, Commence[20];
Result();
void Rcalculate();
void Rdisplay();
};

4.1. Which type of Inheritance is shown in the program?
4.2. Specify the visibility mode of base classes.
4.3 Give the sequence of Constructor/Destructor Invocation when object of class Result is created.
4.4. Name the base class(/es) and derived class (/es).
4.5 Give number of bytes to be occupied by the object of the following class:
(a) Personal
(b) Marks
(c) Result
4.6. Write the names of data members accessible from die object of class Result.
4.7. Write the names of all member functions accessible from the object of class Result.
4.8 Write the names of all members accessible from member functions of class Result.
Answer:
4.1 Multilevel Inheritance
4.2 For Marks class – private visibility
For Result class – public visibility
4.3 Constructors Personal, Marks and Result be executed.
Destructors Result, Marks and Personal will be executed.
4.4 Base classes : Personal and Marks
Derived classes : Marks and Result

4.5 a) Personal class object requires 28 bytes (using Dev C++)
b) Marks class object requires 53 bytes (using Dev C++)
c) Result class requires 82 bytes (using Dev C++)

4.6 Data members FinalGrade, Commence(Own class members) alone can be accessed.
No members inherited under public, so base class members can not be accessed.

4.7 Member functions
Rcalculate( ), Rdisplay (own class member functions)
Mentry, Mdisplay (derived from Marks class) alone can be accessed.
Personal class public member functions can not be accessed because Marks class inherited under private visibility mode.

4.8 1) Data members

• Total, Agg, Final Grade and Commence of its own class
• M, Grade from Marks class can be accessed.

Personal class data members can not be accessed because Marks class inherited under private visibility mode.

2) Member functions
Mentry and Mdisplay from Marks class can be invoked from Result class member
Personal class member-functions can not be accessed because Marks class inherited under private visibility mode.

Question 5.
Write the output of the following program.
#include<iostream>
using namespace std;
class A
{
protected:
int x;
public:
void show()
{
cout<<“x = “<<x<<endl;
}
A()
{
cout<<endl<<” I am class A “<<endl;
}
~A()
{
cout<<endl<<” Bye”;
}
};
class B : public A
{
protected:
int y;
public:
B(int x, int y)
{
//this -> is used to denote the objects datamember this->x = x;
//this -> is used to denote the objects datamember this->y = y;
}
B()
{
cout<<endl<<“I am class B”<<endl;
}
~B()
{
cout<<endl<<” Bye”;
}
void show()
{
cout<<“x = “<<x<<endl;
cout<<“y = “<<y<<endl;
}
};
int main()
{
A objA;
B objB(30, 20);
objB.show();
return 0;
}
Output:

Question 6.
Debug the following program.
Output:
—————
15
14
13

Program :
%include(iostream.h)
#include<conio.h>
Class A
{
public;
int al,a2:a3;
void getdata[]
{
a1=15;
a2=13;a3=13;
}
}
Class B:: public A()
{
PUBLIC
voidfunc()
{
int b1:b2:b3;
A::getdata[];
b1=a1;
b2=a2;
a3=a3;
cout<<b1<<‘\t'<<b2<<‘t\'<<b3;
}
void main()
{
clrscr()
B der;
derl:func();
getch();
}
Answer:
Modified Error Free Program :
using namespace std;
#include<iostream>
#include<conio.h>
class A
{
public:
int a1,a2,a3;
void getdata()
{
a1=15;
a2=14;
a3=13;
}
};
class B : public A
{
public:
void func()
{
int b1,b2,b3;
A::getdata();
b1=a1;
b2=a2;
b3=a3;
cout<<b1<<‘\n'<<b2<<‘\n'<<b3;
}
};
int main()
{
B der;
der.func();
getch();
return 0;
}

11th Computer Science Guide Inheritance Additional Questions and Answers

Choose The Correct Answer:

Question 1.
When a derived class inherits only from one base class, it is known as ………………
(a) multiple inheritances
(b) multilevel inheritance
(c) hierarchical inheritance
(d) single inheritance
Answer:
(d) single inheritance

Question 2.
_____ enables new class and its objects to take on the properties of the existing classes.
a) Inheritance
b) Encapsulation
c) Overriding
d) None of these
Answer:
a) Inheritance

Question 3.
When more than one derived classes are created from a single base class, it is called ………………
(a) inheritance
(b) hybrid inheritance
(c) hierarchical inheritance
(d) multiple inheritances
Answer:
(c) hierarchical inheritance

Question 4.
A class that inherits from a superclass is called a _______ class.
a) Sub
b) Base class
c) Derived
d) Sub or Derived
Answer:
d) Sub or Derived

Question 5.
The ……………… are invoked in reverse order.
(a) constructor
(b) destructor
(c) pointer
(d) operator
Answer:
(b) destructor

Question 6.
There are ________ types of inheritance,
a) Two
b) Three
c) Four
d) Five
Answer:
d) Five

Question 7.
_________ inheritance is a type of inheritance.
a) Single or Hybrid
b) Multilevel / Hierarchical
c) Multiple
d) All the above
Answer:
d) All the above

Question 8.
When a derived class inherits only from one base class, it is known as ________ inheritance.
a) Single
b) Multilevel / Hierarchical
c) Multiple
d) Hybrid
Answer:
a) Single

Question 9.
When a derived class inherits from multiple base classes it is known as _________ inheritance.
a) Single
b) Multilevel / Hierarchical
c) Multiple
d) Hybrid
Answer:
c) Multiple

Question 10.
When more than one derived classes are created from a single base class, it is known
as_________inheritance.
a) Single
b) Hierarchical
c) Multiple
d) Hybrid
Answer:
b) Hierarchical

Question 11.
The transitive nature of inheritance is itself reflected by _____ form of inheritance.
a) Single
b) Multilevel
c) Multiple
d) Hybrid
Answer:
b) Multilevel

Question 12.
When a class is derived from a class which is a derived class – then it is referred to as ______ inheritance.
a) Single
b) Multilevel
c) Multiple
d) Hybrid
Answer:
b) Multilevel

Question 13.
When there is a combination of more than one type of inheritance, it is known as ________ inheritance.
a) Single
b) Multilevel
c) Multiple
d) Hybrid
Answer:
d) Hybrid

Question 14.
Hybrid inheritance may be a combination of ________inheritance.
a) Multilevel and Multiple
b) Hierarchical and Multilevel
c) Hierarchical, Multilevel and Multiple
d) All the above
Answer:
d) All the above

Question 15.
The order of inheritance by derived class, to inherit the base class is ________
a) Left to Right
b) Right to Left
c) Top to Bottom
d) None of these
Answer:
a) Left to Right

Question 16.
In ________ inheritance the base classes dc not have any relationship between them,
a) Single
b) Multilevel
c) Hybrid
d) Multiple
Answer:
d) Multiple

Question 17.
In ________inheritance a derived class itself acts as a base class to derive another class.
a) Single
b) Multilevel
c) Multiple
d) Multiple
Answer:
b) Multilevel

Question 18.
_________ inheritance is similar to relation between grandfather, father and child,
a) Single
b) Multilevel
c) Multiple
d) Multiple
Answer:
b) Multilevel

Question 19.
A class without any declaration will have ________byte size.
a) 1
b) 0
b) 2
d) 10
Answer:
a) 1

Question 20.
class x{}; x occupies
a) 1
b) 0
b) 2
d) 10
Answer:
a) 1

Question 21.
In inheritance, which member of the base class will be acquired by the derived class is done by using ________ .
a) Visibility modes
b) Data members
c) Member functions
d) None of these
Answer:
a) Visibility modes

Question 22.
The accessibility of base class by the derived class is controlled by ________
a) Visibility modes
b) Data members
c) Member functions
d) None of these
Answer:
a) Visibility modes

Question 23.
_______ is a visibility modes.
a) private
b) public
c) protected
d) All the above
Answer:
d) All the above

Question 24.
The default visibility mode is ________
a) private
b) public
c) protected
d) All the above
Answer:
a) private

Question 25.
When a base class is inherited with ________ visibility mode the public and protected members of the base class become ‘private’ members of the derived class.
a) private
b) public
c) protected
d) All the above
Answer:
a) private

Question 26.
When a base class is inherited with ________ visibility mode the protected and public members of the base class become ‘protected members’ of the derived class,
a) private
b) public
c) protected
d) All the above
Answer:
c) protected

Question 27.
When a base class is inherited with ________ visibility mode, the protected members of the base class will be inherited as protected members of the derived class and the public members of the base class will be inherited as public members of the derived class.
a) private
b) public
c) protected
d) All the above
Answer:
b) public

Question 28.
When classes are inherited with ________the private members of the base class are not inherited they are only visible.
a) private
b) public
c) protected
d) Either A or B or C
Answer:
d) Either A or B or C

Question 29.
When classes are inherited with ________ the private members of the base class are continue to exist in derived classes, and cannot be accessed.
a) private
b) public
c) protected
d) Either A or B or C
Answer:
d) Either A or B or C

Question 30.
________inheritance should be used when you want the features of the base class to be available to the derived class but not to the classes that are derived from the derived class.
a) private
b) public
c) protected
d) Either A or B or C
Answer:
a) private

Question 31.
________ inheritance should be used when features of base class to be available only to the derived class members but not to the outside world.
a) private
b) public
c) protected
d) Either A or B or C
Answer:
c) protected

Question 32.
_____ inheritance can be used when features of base class to be available the derived class members and also to the outside world.
a) private
b) public
c) protected
d) Either A or B or C
Answer:
b) public

Question 33.
When an object of the derived class is created, the compiler first call the ________class constructor.
a) Base
b) Derived
c) Either Base or Derived
d) None of these
Answer:
a) Base

Question 34.
When the object of a derived class expires first the ________class destructor is invoked.
a) Base
b) Derived
c) Either Base or Derived
d) None of these
Answer:
b) Derived

Question 35.
The ________ are executed in the order of inherited class.
a) Constructors
b) Destructors
c) Either A or B
d) None of these
Answer:
a) Constructors

Question 36.
The ________ are executed in the reverse order.
a) Constructors
b) Destructors
c) Either A or B
d) None of these
Answer:
b) Destructors

Question 37.
If there are multiple base classes, then it starts executing from the ________base class.
a) Leftmost
b) Rightmost
c) Compiler decided
d) None of these
Answer:
a) Leftmost

Question 38.
________ members of the base class can be indirectly accessed by the derived class using the public or protected member function of the base class.
a) private
b) public
c) protected
d) Either A or B or C
Answer:
a) private

Question 39.
________ member function has the access privilege for the private members of the base class.
a) public
b) protected
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 40.
________ functions can access the private members.
a) Member
b) Non-member
c) Destructor
d) None of these
Answer:
a) Member

Question 41.
In case of inheritance there are situations where the member function of the base class and derived classes have the same name. The ________operator resolves this problem.
a) Conditional
b) Membership
c) Scope resolution
d) None of these
Answer:
c) Scope resolution

Question 42.
When a derived class member function has the same name as that of its base class member function, the derived class member function ________the base class’s inherited function.
a) Shadows
b) Hides
c) Either A or B
d) None of these
Answer:
c) Either A or B

Question 43.
When a derived class member function has the same name as that of its base class member function, the derived class member function shadows/hides the base class’s inherited function is called function ________
a) Overriding
b) Overloading
c) Shadowing
d) Either A or C
Answer:
d) Either A or C

Question 44.
________ pointer is a constant pointer that holds the memory address of the current object.
a) this
b) void
c) new
d) None of these
Answer:
a) this

Question 45.
________pointer is useful when the argument variable name in the member function and the data member name are same.
a) this
b) void
c) new
d) None of these
Answer:
a) this

Very Short Answers (2 Marks)

Question 1.
Write a short note on hierarchical inheritance.
Answer:
When more than one derived class is created from a single base class, it is known as Hierarchical inheritance.

Question 2.
What are the types of inheritance?
Answer:
There are different types of inheritance viz., Single Inheritance, Multiple inheritance, Multilevel inheritance, hybrid inheritance and hierarchical inheritance.

Question 3.
Give the syntax of deriving a class.
Answer:
Syntax:
class derived_dass_name :visibility_mode base_dass_name
{
// members of derivedclass
};

Question 4.
Write note on this pointer.
Answer:
‘this’ pointer is a constant pointer that holds the memory address of the current object. It identifies the currently calling object. It is useful when the argument variable name in the member function and the data member name are same. To identify the data member it will be given as this->data member name.

Short Answers (3 Marks)

Question 1.
What are inheritance and access control?
Answer:
When you declare a derived class, a visibility mode can precede each base class in the base list of the derived class. This does not alter the access attributes of the individual members of a base class but allows the derived class to access the members of a base class with restriction.

Classes can be derived using any of the three visibility modes:

1. In a public base class, public and protected members of the base class remain public and protected members of the derived class.
2. In a protected base class, public and protected members of the base class are protected members of the derived class.
3. In a private base class, public and protected members of the base class become private members of the derived class.
4. In all these cases, private members of the base class remain private and cannot be used by the derived class.
5. However, it can be indirectly accessed by the derived class using the public or protected member function of the base class since they have the access privilege for the private members of the base class.

Question 2.
Write a program for the working of constructors and destructors under inheritance.
Program
#include<iostream>
using namespace std;
class base
{
public:
base()
{
cout<<“\nConstructor of base class…”;
}
~base()
{
cout<<“\nDestructor of base class….”;
}
};
class derived:public base
{
public :
derived()
{
cout << “\nConstructor of derived …”;
}
~derived()
{
cout << “\nDestructor of derived…”;
}
};
class derived 1 :public derived
{
public :
derived 1()
{
cout << “\nConstructor of derived! //, …”;
}
~derived1()
{
cout << “\nDestructor of derived …”;
}
};
int main()
{
derivedl x;
return 0;
}

Output:
Constructor of base class…
Constructor of derived …
Constructor of derived …
Destructor of derived …
Destructor of derived …
Destructor of base class….

Question 3.
What about access control in a publicly derived class?
Answer:
From a publicly derived class, public and protected members of the base class remain public and protected members of the derived class. The public members can be accessed by the object of the derived class similar to its own members in public.

Question 4.
What about access control in the privately derived class?
Answer:
From a privately derived class, public and protected members of the base class become private members of the derived class. Hence it is not possible to access the derived members using the object of the derived class. The Derived members are invoked by calling it from the publicly defined members.

Explain in Detail

Question 1.
Write a program to implement single Inheritance.
Program
# include <iostream>
using namespace std;
class student //base class
{
private :
char name[20];
int rno;
public:
void acceptnameO
{
cout<<“\n Enter roll no and name ..”;
cin>>rno>>name;
}
void displayname()
{
cout<<“\n Roll no :-“<<rno;
cout<<“\n Name :-“<<name<<endl;
}
};
class exam : public student
//derived class with single base class
{
public:
int markl, mark2 ,mark3,mark4,marks, mark6, total;
void acceptmark()
{
cout<<“\n Enter lang, eng, phy, che, esc, mat marks..
cin>>mark1>>mark2>>mark3>>
mark4>>mark5>>mark6;
}
void displaymark()
{
cout<<“\n\t\t, Marks Obtained
cout<<“\n Language.. “<<mark1;
cout<<“\n English .. “<<mark2;
cout<<“\n Physics .. “<<mark3;
cout<<“\n Chemistry.. “<<mark4;
cout<<“\n Comp.sci.. “<<mark5;
cout«”\n Maths .. “<<mark6;
}
};
int main()
{
exam e1;
el.acceptname();
//calling base class function using derived
class object
e1.acceptmark();
e1.displayname();
//calling base class function using derived
class object
e1l.displaymark();
return 0;
}
Output
Enter roll no and name . . 1201
KANNAN
Enter lang,eng,phy,che,esc,mat
marks.. 100 100 100 100 100 100
Roll no:-1201
Name:-KANNAN
Marks Obtained
Language.. 100
English .. 100
Physics .. 100
Chemistry.. 100
Comp.sci.. 100
Maths .. 100

Question 2.
Write a program to implement multiple inheritance.
Program :
# include <iostream>
using namespace std;
class student //base class
{
private :
char name[20];
int rno;
public:
void acceptname()
{
cout<<“\n Enter roll no and name.. “;
cin>>rno>>name;
}
void displayname()
{
cout<<“\n Roll no :-“<<rno;
cout<<“\n Name:-” << name << endl;
}
};
class detail //Base class
{
int dd,mm,yy;
char cl[4];
public:
void acceptdob()
{
cout<<“\n Enter date,month,year in digits and class ..”;
cin>>dd>>mm>>yy>>cl;
}
void displaydob()
{
cout<<“\n class:-“<<cl;
cout<<“\t\t DOB : “<<dd«” –
“<<mm<<“-” <<yy<<endl;
}
};
//derived class with multiple base class
class exam: public student, public detail
{
public:
int mark1, mark2 ,mark3,mark4,mark5, mark6, total;
void acceptmark()
{
cout<<“\n Enter lang, eng, phy, che, esc, mat marks..”;
cin>>mark1>>mark2>>mark3>> mark4>>mark5>>mark6;
}
void displaymark()
{
cout<<“\n\t\t Marks Obtained
cout<<“\n Language.. “<<markl;
cout<<“\n English .. “<<mark2;
cout<<“\n Physics .. “<<mark3;
cout<<“\n Chemistry.. “<<mark4;
cout<<“\n Comp.sci.. “<<mark5;
cout<<“\n Maths .. “<<mark6;
}
};
int main()
{
exam e1;
//calling base class function using derived
class object
e1.acceptname();
//calling base class function using derived
class object
e1.acceptdob();
e1.acceptmark();
//calling base class function using derived
class object
e1.displayname();
//calling base class function using derived
class object
e1.displaydob();
e1.displaymark();
return 0;
}
Output:
Enter roll no and name . . 1201 MEENA
Enter date, month, year in digits and
class .. 7 12 2001 XII
Enter lang, eng, phy, che, esc, mat
marks.. 96 98 100 100 100 100
Roll no:-1201
Name MEENA
class:-XII
DOB : 7 – 12 -2001
Marks Obtained
Language..96
English .. 98
Physics .. 100
Chemistry.. 100
Comp.sci.. 100
Maths .. 100

Question 3.
Write a program to implement multilevel inheritance.
Program
# include <iostream>
using namespace std;
class student //base class
{
private :
char name[20];
int rno; public:
void acceptname()
{
cout<<“\n Enter roll no and name.. “;
cin>>rno>>name;
}
void displayname()
{
cout<<“\n Roll no :-“<<rno;
cout<<“\n Name << name <<
endl;
}
};
//derived class with single base class class
exam: public student
{
public:
int mark1, mark2, mark3, mark4, mark5, mark6;
void accept mark()
{
cout<<“\n Enter
lang,eng,phy,che,esc,mat marks..’; cin>>mark1>>mark2>>mark3>> mark4>>mark5>>mark6;
}
void displaymark()
{
cout<<“\n\t\t Marks Obtained
cout<<“\n Language… “<<markl;
cout<<“\n English… “<<mark2;
cout<<“\n Physics… “<<mark3;
cout<<“\n Chemistry… “<<mark4;
cout<<“\n Comp.sci… “<<mark5;
cout<<“\n Maths… “<<mark6;
}
};
class result: public exam
{
int total;
public:
void showresult()
{
total=markl+mark2+mark3+mark 4+mark5+mark6;
cout<<“\nTOTAL MARK SCORED : “<<total;
}
};
int main()
{
result r1;
//calling base class function using derived
class object
r1.acceptname();
//calling base class function which itself is a derived
r1.acceptmark();
// class function using its derived class object
r1.displayname();
//calling base class function
using derived class //object
//calling base class function which itself is a derived
r1.displaymark();
//class function using its derived class object
r1.showresult();
//calling the child class
function
return 0;
}

Output :
Enter roll no and name .. SARATHI
Enter lang,eng,phy,che,csc,mat
marks.. 96 98 100 100 100 100
Roll no:-1201
Name:-SARATHI
Marks Obtained
Language… 96
English… 98
Physics… 100
Chemistry… 100
Comp.sci… 100
Maths… 100
TOTAL MARK SCORED: 594

Question 4.
Write a program to implement hierarchical inheritance.
Program
# include <iostream>
using namespace std;
class student //base class
{
private :
char name[20];
int rno;
public:
void acceptname()
{
cout<<“\n Enter roll no and name..”;
cin>>rno>>name;
}
void displayname()
{
cout<<“\n Roll no :-“<<rno;
cout<<“\n Name :-” <<name <<
endl;
}
};
//derived class with single base class
class qexam: public student
{
public:
int mark1, mark2, mark3, mark4, marks, mark6;
void accent mark()
{
cout<<“\n Enter lang, eng, phy, che, esc, mat marks for quarterly exam”;
cin>>markl>>mark2>>mark3>>mark4>>mark5>>mark6;
}
void displaymark()
cout< <“\n\t\t Marks Obtained in quarterly”;
cout< <“\n Language.. “<<marki;
cout<<”\n English .. “<<mark2;
cout< <“\n Physics .. “<<mark3;
cout< <“\fl Chemistry.. “<<mark4;
cout<<“\n Comp.sci.. “<<mark5;
cout< <“\n Maths .. “<<mark6;
}
};
//derived class with single base class
class hexam : public student
{
public:
int mark1, mark2, mark3, mark4, marks, mark6;
void acceptmark()
{
cout<<“\n Enter lang, eng, phy, che, esc, mat marks for half/early exam..”;
cin>>markl>>mark2>>mark3>>mark4>>mark5>>mark6;
}
void displaymark()
{
cout<<“\n\t\t Marks Obtained in Halfyearly”;
cout<<“\n Language., “<< mark1;
coutcc”\n English .. “<< mark2;
coutcc”\n Physics .. “<< mark3;
coutcc”\n Chemistry.. “<< mark4;
coutcc”\n Comp.sci.. “<< mark5;
coutcc”\n Maths .. “<< mark6;
}
};
int main()
{
qexam q1;
hexam hi;
//calling base class function using derived class object
q1.acceptname();
//calling base class function
q1. acceptmark();
//calling base class function using derived
class object
h1.acceptname();
//calling base class function using derived class object
h1.displayname(); .
h1,acceptmark();
//calling base class- function using its // derived class object
h1.displaymark();
return 0
}
Output:
Enter roll no and name . . 1201
KANNAN
Enter lang,eng,phy,che,esc,mat
marks for quarterly exam. .
95 96 100 98 100 99
Roll no :-1201
Name :-KANNAN
Marks Obtained in quarterly
Language.. 95
English .. 96
Physics .. 100
Chemistry.. 98
Comp.sci.. 100
Maths .. 99
Enter roll no and name . . 1201
KANNAN
Enter lang,eng,phy,che,esc, mat marks for the half-yearly exam.
96 98 100 100 100 100
Roll no:-1201
Name:-KANNAN
Marks Obtained in Halfyearly
Language.. 96
English .. 98
Physics .. 100
Chemistry.. 100
Comp.sci.. 100
Maths .. 100

Question 5.
Write a program to implement hybrid inheritance.
Program
# include <iostream>
using namespace std;
class student //base class
{
private :
char name[20];
int rno; public:
void acceptname()
{
cout<<“\n Enter roll no and name.. cin>>rno>>name;
}
void displayname()
{
cout<<“\n Roll no :-“<<rno;
cou<<“\n Name name <<
endl;
}
};
//derived class with the single base class
class exam: public student
{
public:
int mark1, mark2, mark3, mark4, marks, mark6;
void accept mark()
{
cout<<“\n Enter larig, eng, phy, che, esc,mat marks..”;
cin>>markl>>mark2>>mark3>> mark4>>mark5>>mark6;
}
void displaymark()
{
cout<<“\n\t\t Marks Obtained “;
cout<<“\n Language.. “<<markl;
cout<<“\n English .. “<<mark2;
cout<<“\n Physics .. “<<mark3;
cout<<“\n Chemistry.. “<<mark4;
cout<<“\n Comp.sci.. “<<mark5;
cout<< “\n Maths .. “<<mark6;
}
};
class detail //base classs 2
{
int dd,mm,yy;
char cl[4];
public:
void acceptdob()
{
cout<<“\n Enter date,month,year in digits and class ..”;
cin>>dd>>mm>>yy>>cl;
}
void displaydob()
{
cou<<“\n class :-“<<cl;
cou<<“\t\t DOB : “<<dd<<” – ”
<<mm<<“-” <<yy<<endl;
}
};
//inherits from the exam, which itself is a //derived
class and also from class detail
class result: public exam, public detail
{
int total;
public:
void showresuit()
{
total=markl+mark2+mark3+ mark4+mark5+mark6;
cout<<“\nTOTAL MARK SCORED: ” <<total;
}
};
class detail //base classs 2
{
int dd,mm,yy;
char cl[4];
public:
void acceptdob()
{
cout<<“\n Enter date,month,year in digits and class ..
cin>>dd>>mm>>yy>>cl;
}
void displaydob()
{
cout<<“\n class :-“<<cl;
cout<<“\t\t DOB : “<<dd<<” – ”
<<mm<<“-” <<yy<<endl;
}
};
//inherits from the exam, which itself is a //derived class and also from class detail class result: public exam, public detail
{
int total;
public:
void showresuit()
{
total = markl + mark2-i-mark3 + mark4+mark5+mark6;
cout<<“\nTOTAL MARK SCORED : ” <<total;
}
};
int main()
{
result r1;
//calling base class function using derived class object
r1.acceptname();
//calling base class which itsel is a derived class function using its derived class object
r1.acceptmark();
r1.acceptdob();
cout<<“\n\n\t\t MARKS STATEMENT”; //calling base class function using derived class object
r1.displayname();
r1.displaydob();
//calling base class which itsel is a derived class function using its derived class object
r1.displaymark();
//calling the child class function
r1.showresuit();
return 0;
>
Output:
Enter roll no and name .. 1201 RAGU
Enter lang,eng,phy,che,esc,mat
marks.. 96 98 100 100 100 100
Enter date,month,year in digits and class .. 7 12 2001 XII
MARKS STATEMENT
Roll no :-1201
Name :-RAGU
class : -XII
DOB : 7 – 12 -2001
Marks Obtained
Language..96
English .. 98
Physics .. 100
Chemistry.. 100
Comp.sci.. 100
Maths .. 100
TOTAL MARK SCORED: 594

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Chemistry Guide Pdf Chapter 7 Thermodynamics Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Chemistry Solutions Chapter 7 Thermodynamics

11th Chemistry Guide Thermodynamics Text Book Back Questions and Answers

Textual Questions:

I. Choose the best answer:

Question 1.
The amount of heat exchanged with the surrounding at constant temperature and pressure is given by the quantity
(a) ∆E
(b) ∆H
(c) ∆S
(d) ∆G
Answer:
(b) ∆H

Question 2.
All the naturally occurring processes proceed spontaneously in a direction which leads to
(a) decrease in entropy
(b) increase in enthalpy
(c) increase in free energy
(d) decrease in free energy
Answer:
(d) decrease in free energy

Question 3.
In an adiabatic process, which of the following is true?
(a) q = w
(b) q = 0
(c) ∆E = q
(d) P∆V = 0
Answer:
(b) q = 0

Question 4.
In a reversible process, the change in entropy of the universe is
(a) > 0
(b) ≥ 0
(c) <0
(d) = 0
Answer:
(d) = 0

Question 5.
In an adiabatic expansionof an ideal gas
(a) w = – ∆U
(b) w = ∆U + ∆H
(c) ∆U = 0
(d) w = 0
Answer:
(a) w = – ∆U

Question 6.
The intensive property among the quantities below is
(a) mass
(b) volume
(c) enthalpy
(d) mass/volume
Answer:
(d) mass/volume

Question 7.
An ideal gas expands from the volume of 1 × 10^-3 m³ to 1 × 10^-2 m³ at 300 K against a constant pressure at 1 × 10⁵ Nm^-2. The work done is
(a) -900 J
(b) 900 kJ
(c) 270 kJ
(d) – 900 kJ
Answer:
(a) -900 J

Question 8.
Heat of combustion is always
(a) positive
(b) negative
(c) zero
(d) either positive or negative
Answer:
(b) negative

Question 9.
The heat of formation of CO and CO₂ are -26.4 kCal and -94 kCal, respectively. Heat of combustion of carbon monoxide will be
(a) + 26.4 kcal
(b) – 67.6 kcal
(c) – 120.6 kcal
(d) + 52.8 kcal
Answer:
(b) – 67.6 kcal

Question 10.
C(diamond) → C(graphite), ∆H = -ve, this indicates that
(a) graphite is more stable than diamond
(b) graphite has more energy than diamond
(c) both are equally stable
(d) stability cannot be predicted
Answer:
(a) graphite is more stable than diamond

Question 11.
The enthalpies of formation of Al₂O₃ and Cr₂O₃ are – 1596 kJ and – 1134 kJ, respectively.
∆H for the reaction 2Al + Cr₂O₃ → 2Cr + Al₂O₃ is
(a) – 1365 kJ
(b) 2730 kJ
(c) – 2730 kJ
(d) -462 kJ
Answer:
(d) -462 kJ

Question 12.
Which of the following is not a thermodynamic function?
(a) internal energy
(b) enthalpy
(c) entropy
(d) frictional energy
Answer:
(d) frictional energy

Question 13.
If one mole of ammonia and one mole of hydrogen chloride are mixed in a closed container to form ammonium chloride gas, then
(a) ∆H > ∆U
(b) ∆H – ∆U = 0
(c) ∆H + ∆U = 0
(d) ∆H < ∆U
Answer:
(d) ∆H < ∆U

Question 14.
Change in internal energy, when 4 kJ of work is done on the system and 1 kJ of heat is given out by the system is
(a) +1 kJ
(b) -5 kJ
(c) +3 kJ
(d) -3 kJ
Answer:
(c) +3 kJ

Question 15.
The work is done by the liberated gas when 55.85 g of iron (molar mass 55.85 g mol^-1) reacts with hydrochloric acid in an open beaker at 25°C
(a) -2.48 kJ
(b) -2.22 kJ
(c) +2.22 kJ
(d) +2.48 kJ
Answer:
(a) -2.48 kJ

Question 16.
The value of ∆H for cooling 2 moles of an ideal monatomic gas from 1250°C to 250°C at constant pressure will be [given C_p = \(\frac{5}{2}\)R]
(a) – 250 R
(b) – 500 R
(c) 500 R
(d) + 250 R
Answer:
(b) – 500 R

Question 17.
Given that C_(g) + O_2(g) → CO_2(g) ∆H° = – a kJ;
2 CO_(g) + O_2(g) → 2CO_2(g) ∆H° = -b kJ; Calculate the ∆H° for the reaction C_(g) + ½O_2(g) → CO_(g)
(a) \(\frac{b+2 a}{2}\)
(b) 2a – b
(c) \(\frac{2 a-b}{2}\)
(d) \(\frac{b-2 a}{2}\)
Answer:
(d) \(\frac{b-2 a}{2}\)

Question 18.
When 15.68 litres of a gas mixture of methane and propane are fully combusted at 0° C and 1 atmosphere, 32 litres of oxygen at the same temperature and pressure are consumed. The amount of heat released from this combustion in kJ is (∆H_C(CH4)) = – 890 kJ mol and ∆H_C(C3H8) = -2220 kJ mol^-1)
(a) -889 kJ
(b) -1390 kJ
(c) -3180 kJ
(d) -632.68 kJ
Answer:
(d) -632.68 kJ

Question 19.
The bond dissociation energy of methane and ethane are 360 kJ mol^-1 and 620 kJ mol^-1 respectively. Then, the bond dissociation energy of the C-C bond is
(a) 170 kJ mol^-1
(b) 50 kJ mol^-1
(c) 80 kJ mol^-1
(d) 220 kJ mol^-1
Answer:
(c) 80 kJ mol^-1

Question 20.
The correct thermodynamic conditions for the spontaneous reaction at all temperature is
(a) ∆H < 0 and ∆S > 0
(b) ∆H < 0 and ∆S < 0
(c) ∆H > 0 and ∆S = 0
(d) ∆H > 0 and ∆S > 0
Answer:
(a) ∆H < 0 and ∆S > 0

Question 21.
The temperature of the system decreases in an
(a) Isothermal expansion
(b) Isothermal Compression
(c) adiabatic expansion
(d) adiabatic compression
Answer:
(c) adiabatic expansion

Question 22.
In an isothermal reversible compression of an ideal gas the sign of q, ∆S and w are respectively
(a) +, -, –
(b) -, +, –
(c) +, -, +
(d) -, -, +
Answer:
(d) -, -, +

Question 23.
Molar heat of vapourisation of a liquid is 4.8 kJ mol^-1 If the entropy change is 16 J mol^-1 K^-1. the boiling point of the liquid is
(a) 323 K
(b) 27°C
(c) 164 K
(d) 0.3 K
Answer:
(b) 27°C

Question 24.
∆S is expected to be maximum for the reaction
(a) Ca(S) + 1/2 O₂(g) → CaO(S)
(b) C(S) + O₂(g) → CO₂(g)
(c) N₂(g) + O₂(g) → 2NO(g)
(d) CaCO₃(S) → CaO(S) + CO₂(g)
Answer:
(d) CaCO₃(S) → CaO(S) + CO₂(g)

Question 25.
The values of ∆H and ∆S for a reaction are respectively 30 kJ mol^-1 and 100 JK^-1 mol^-1. Then the temperature above which the reaction will become spontaneous is
(a) 300 K
(b) 30 K
(c) 100 K
(d) 20°C
Answer:
(a) 300 K

II. Write brief answers to the following questions:

Question 26.
State the first law of thermodynamics.
Answer:
The first law of thermodynamics states that “the total energy of an isolated system remains constant though it may change from one form to another”
(or)
Energy can neither be created nor destroyed but may be converted from one form to another.

Question 27.
Define Hess’s law of constant heat summation.
Answer:
The heat changes in chemical reactions are equal to the difference in internal energy (∆U) or heat content (∆H) of the products and reactants, depending upon whether the reaction is studied at constant volume or constant pressure. Since ∆U and ∆H are functions of the state of the system, the heat evolved or absorbed in a given reaction depends only on the initial state and final state of the system and not on the path or the steps by which the change takes place.

Question 28.
Explain intensive properties with two examples.
Answer:
The property that is independent of the mass or size of the system is called an intensive property.
e.g., Refractive index and surface tension.

Question 29.
Define the following terms:
(a) isothermal process
(b) adiabatic process
(c) isobaric process
(d) isochoric process
Answer:
(a) isothermal process: It is defined as one in which the temperature of the system remains constant, during the change from its initial to final states.

(b) Adiabatic process: It is defined as one in which there is no exchange of heat (q) between the system and surrounding during operations.

(c) Isobaric process: It is defined as one in which the pressure of the system remains constant during its change from the initial to the final state.

(d) Isochoric process: It is defined as one in which the volume of the system remains constant during its change from initial to the final stage of the process.

Question 30.
What is the usual definition of entropy? What is the unit of entropy?
Answer:
Entropy is a measure of the molecular disorder (randomness) of a system.
The thermodynamic definition of entropy is concerned with the change in entropy that occurs as a result of a process.
It is defined as, dS = dq_rev /T

Question 31.
Predict the feasibility of a reaction when

1. both ∆H and ∆S positive
2. both ∆H and ∆S negative
3. ∆H decreases but ∆S increases

Answer:

1. When both ∆H and ∆S are positive, the reaction is not feasible.
2. When both ∆H and ∆S are negative, the reaction is not feasible.
3. When ∆H decreases but ∆S increases, the reaction is feasible.

Question 32.
Define is Gibb’s free energy.
Answer:
Gibbs free energy is defined as the part of the total energy of a system that can be converted (or) available for conversion into work.
G = H -TS,
where G = Gibb’s free energy
H = enthalpy
T = temperature
S = entropy

Question 33.
Define enthalpy of combustion.
Answer:
The heat of combustion of a substance is defined as “The change in enthalpy of a system when one mole of the substance is completely burnt in excess of air or oxygen”. It is denoted by ∆H_C.

Question 34.
Define molar heat capacity. Give its unit.
Answer:
The heat capacity for 1 mole of substance, is called molar heat capacity (cm). It is defined as “The amount of heat absorbed by one mole of the substance to raise its temperature by 1 kelvin”.
The SI unit of molar heat capacity is JK^-1 mol^-1

Question 35.
Define the calorific value of food. What is the unit of calorific value?
Answer:
The calorific value is defined as the amount of heat produced in calories (or joules) when one gram of the substance is completely burnt. The SI unit of calorific value is J kg^-1. However, it is usually expressed in cal g^-1.

Question 36.
Define enthalpy of neutralization.
Answer:
The enthalpy of neutralization is defined as the change in enthalpy of the system when one gram equivalent of an acid is neutralized by one gram equivalent of a base or vice versa in dilute solution.
H⁺_(aq) + OH^–_(aq) → H₂O_(l) = 57.32 kJ.

Question 37.
What is lattice energy?
Answer:
Lattice energy is defined as the amount of energy required to completely remove the constituent ions from its crystal lattice to an infinite distance. It is also referred as lattice enthalpy.

Question 38.
What are state and path functions? Give two examples.
Answer:

• The variables like P. V, T, and ‘n’ that are used to describe the state of the system are called state functions. e.g. pressure, volume, temperature, internal energy, enthalpy, and free energy.
• A path function is a thermodynamic property of the system whose value depends on the path or manner by which the system goes from its initial to the final state. e.g., work (w) and heat (q).

Question 39.
Give Kelvin a statement of the second law of thermodynamics.
Answer:
Kelvin-Planck statement: It is impossible to take heat from a hotter reservoir and convert a cyclic process heat to a cooler reservoir.

Question 40.
The equilibrium constant of a reaction is 10, what will be the sign of ∆G? Will this reaction be spontaneous?
Answer:
∆G = -2.303 RT logK_eq
Substituting the known values of R, T and K_eq
R = 8.314(JK^-1 mol^-1)
T = 300 K
K_eq = 10
∆G = –2.303 8.314(JK^-1) 300(K) log 10
= -5744.14 J/mol
= -5.744 KJ/mol
∆G < 0, then it is spontaneous.

Question 41.
Enthalpy of neutralization is always a constant when a strong acid is neutralized by a strong base: account for the statement.
Answer:

1. Enthalpy of neutralization of a strong acid by a strong base is always a constant and it is equal to -57.32 kJ irrespective of which acid or base is used.
2. Because strong acid or strong base means it is completely ionized in solution state. For e.g., NaOH (strong base) is neutralized by HCl (strong acid), due to their complete ionization, the net reaction takes place is only water formation.

So the enthalpy of neutralization is always constant for strong acid by a strong base.
H⁺Cl^– + Na⁺OH^– → Na⁺Cl^– + H₂O
H⁺NO₃⁺ + K⁺OH^– → K⁺NO₃⁺+ H₂O
(Net reaction) H⁺ + OH^– → H₂O ∆H = -57.32 kJ

Question 42.
State the third law of thermodynamics.
Answer:
The third law of thermodynamics states that the entropy of pure crystalline substance at absolute zero is zero. Otherwise, it can be stated as it is impossible to lower the temperature of an object to absolute zero in a finite number of steps. Mathematically,
lim_T→0 S = 0 for a perfectly ordered crystalline state.

Question 43.
Write down the Born-Haber cycle for the formation of CaCl₂.
Answer:

Step 1:
Solid calcium is converted to gaseous state (Enthalpy of atomization)
Ca_(S) → Ca_(g) Ca(g)                         ∆H°_a = 178 KJ/mol
Step 2:
The calcium is converted to ionic form
(divalent cation): (Ionisation enthalpy)
Ca → Ca⁺ + e^–                          ∆H°_IE = 590 kJ
Ca → Ca²⁺ + e^–                        ∆H°_IE = 590 KJ
Step 3:
Atomisation of chlorine molecule to chlorine atom: (Atomisation enthalpy)
\(\frac{1}{2}\)Cl₂ → Cl               ∆H°_Cl-Cl = 121 KJ
For two chlorine atoms required, atomistion energy = 2 × 121 = 242 KJ/mol
Step 4:
Convrsion of chlorine atom into ion:(Electron affinity)
Cl + e^– → Cl^–;                           ∆H°_ea = – 364KJ
Step 5:
Finally the two ions join together by lattice energy as: (here two Cl^– ions are involved)
Ca²⁺ + 2Cl^– → CaCl₂

Hence Lattice energy = Heat of formation – heat of atomization – dissociation energy – (sum of ionization energies) – (sum of electron affinities)
Since, heat of formation (i.e standard enthalpy of formation ) of CaCl₂ = – 796KJ/mol
Lattice energy = -796 -178 -242 -(590 + 1145) – (2 × – 364) = -2223KJ/mol

Question 44.
Identify the state and path functions out of the following: (a) Enthalpy (b) Entropy (c) Heat (d) Temperature (e) Work (f) Free energy.
Answer:
State function:
Enthalpy, Temperature, Free energy, Entropy
Path function:
Work, Heat.

Question 45.
State the various statements of the second law of thermodynamics.
Answer:
1. Entropy statement:
Whenever a spontaneous process takes place, it is accompanied by an increase in the total entropy of the universe”.

2. Kelvin-Planck statement:
it is impossible to take heat from a hotter reservoir and convert it completely into work by a cyclic process without transferring a part of heat to a cooler reservoir.

3. Efficiency statement:
Even an ideal, frictionless engine cannot convert 100% of its input heat into work.
Efficiency = \(\frac{\mathrm{T}_{1}-\mathrm{T}_{2}}{\mathrm{T}_{1}}\)
% Efficiency = \(\left[\frac{\mathrm{T}_{1}-\mathrm{T}_{2}}{\mathrm{T}_{1}}\right]\) x 100
% Efficiency = \(\left[\frac{\text { Output }}{\text { Input }}\right]\) x 100
% Efficiency < 100%

4. Clausius statement:
Heat flows spontaneously from hot objects to cold objects and to get it to flow in the opposite direction, we have to spend some work.

Question 46.
What are spontaneous reactions? What are the conditions for the spontaneity of a process?
Answer:

1. A reaction that occurs under the given set of conditions without any external driving force is called a spontaneous reaction.
2. The spontaneity of any process depends on three different factors.
3. If the enthalpy change of a process is negative, then the process is exothermic and may be spontaneous. (∆H is negative)
4. If the entropy change of a process is positive, then the process may occur spontaneously. (∆S is positive)
5. The gibbs free energy which is the combination of the above two (∆H – T∆S) should be negative for a reaction to occur spontaneously, i.e. the necessary condition for a reaction to be spontaneous is ∆H – T∆S < 0
6. For spontaneous process,
   ∆S_total > 0, ∆G < 0, ∆S < 0

Question 47.
List the characteristics of internal energy.
Answer:

• The internal energy of a system is an extensive property. It depends on the number of substances present in the system.
• The internal energy of a system is a state function. It depends only upon the state variables (T, P, V. n) of the system.
• The change in internal energy is as ∆U = U₂ – U₁
• In a cyclic process, there is no energy change. ∆U_(cyclic) = 0.
• If the internal energy of the system at the final state (U_f) is less than the internal energy of the
  system at its initial state (U_i), then ∆U would be negative.
• if U_f < U_i ∆U = U_f – U_i = -ve
• if U_f > U_i ∆U = U_f – U_i = +ve

Question 48.
Explain how heat absorbed at constant volume is measured using a bomb calorimeter with a neat diagram.
Answer:
The calorimeter is used for measuring the amount of heat change in a chemical or physical change. In calorimetry, the temperature change in the process is measured which is directly proportional to the heat capacity. By using the expression C = \(\frac{q}{m \Delta T}\), we can calculate the amount of heat change in the process. Calorimetric measurements are made under two different conditions
(i) At constant volume (qV)
(ii) At constant pressure (qp)
(A) ∆U Measurements:
For chemical reactions, heat evolved at constant volume, is measured in a bomb calorimeter.

The inner vessel (the bomb) and its cover are made of strong steel. The cover is fitted tightly to the vessel by means of metal lid and screws.

A weighed amount of the substance is taken in a platinum cup connected with electrical wires for striking an arc instantly to kindle combustion. The bomb is then tightly closed and pressurized with excess oxygen. The bomb is immersed in water, in the inner volume of the calorimeter. A stirrer is placed in the space between the wall of the calorimeter and the bomb, so that water can be stirred, uniformly. The reaction is started by striking the substance through electrical heating.

A known amount of combustible substance is burnt in oxygen in the bomb. Heat evolved during the reaction is absorbed by the calorimeter as well as the water in which the bomb is immersed. The change in temperature is measured using a Beckman thermometer. Since the bomb is sealed its volume does not change and hence the heat measurements is equal to the heat of combustion at a constant volume (∆U)_c.

The amount of heat produced in the reaction (∆U)_c is, equal to the sum of the heat abosrbed by the calorimeter and water.
Heat absorbed by the calorimeter
q₁ = k.∆T
where k is a calorimeter constant equal to mc Cc ( me is mass of the calorimeter and Cc is heat capacity of calorimeter)
Heat absorbed by the water q₂ = m_w C_w ∆T
where mw is molar mass of water
C_w is molar heat capacity of water (4,184 kJ K^-1 mol^-1)
Therefore ∆U_c = q₁ + q₂
= k.∆T + m_w C_w ∆T
= (k + m_w C_w)∆T

Calorimeter constant can be determined by burning a known mass of standard sample (benzoic acid) for which the heat of combustion is known (-3227 kJ mol^-1). The enthalpy of combustion at constant pressure of the substance is calculated from the equation
∆H°_c (pressure) = ∆U°_c (Vol) + ∆n_gRT

Question 49.
Calculate the work involved in expansion and 1 compression process.
Answer:
Work involved in expansion and compression processes:
In most thermodynamic calculations we are dealing with the evaluation of work involved in the expansion or compression of gases. The essential condition for expansion or compression of a system; is that there should be difference between external pressure (P_ext) and internal pressure (P_int).

For understanding pressure-volume work, let us consider a cylinder which contains V moles of an ideal gas fitted with a frictionless piston of cross sectional area A. The total volume of the gas inside is V and pressure of the gas inside is P_int. If the external pressure P_ext is greater than P_int, the piston moves inward till the pressure inside becomes equal to P_ext. Let this change be achieved in a single step
and the final volume be V_f.In this case, the work is done on the system (+w). It can be calculated as follows
w = -F.∆x ……….(1)
where dx is the distance moved by the piston during the compression and F is the force acting on the gas.

F = P_extA ……….(2)
Substituting (2) in (1)
w = – P_ext. A. ∆x
A .∆x = change in volume = V_f – V_i
w = -P_ext.{V_f – V_i) ……….(3)
w = -P_ext. (-∆V) …………(4)
= P_ext.∆V

Since work is done on the system, it is a positive quantity.
If the pressure is not constant, but changes during the process such that it is always infinitesimally greater than the pressure of the gas, then, at each stage of compression, the volume decreases by an infinitesimal amount, dV. In such a case we can calculate the work done on the gas by the relation
W_rev = – \(\int_{V_{i}}^{v_{f}}\) p_ext dV.
In a compression process, Pext the external pressure is always greater than the pressure of the system.
i.e., P_ext = (P_int + dP)
In an expansion process, the external pressure is always less than the pressure of the system
i.e., P_ext = (P_int – dP)

When pressure is not constant and changes in infinitesimally small steps (reversible conditions) during compression from V_i to V_f. the P-V plot looks like in figure. Work done on the gas is represented by the shaded area.
In general case we can write,
P_ext = (P_int ± dP). Such processes are called reversible processes. For a compression process work can be related to internal pressure of the system under reversible conditions by writing equation
W_rev = – \(\int_{V_{i}}^{v_{f}}\) P_int dV
For a given system with an ideal gas
P_int V = nRT
p_int = \(\frac{n R T}{V}\)
W_rev = – \(\int_{V_{i}}^{v_{f}}\) \(\frac{n R T}{V}\) dV
W_rev = – nRTln(\(\frac{V_{f}}{V_{i}}\))
W_rev= -2.303nRTlog\(\frac{V_{f}}{V_{i}}\) ………….(5)

If V_f > V_i (expansion), the sign of work done by the process is negative.
If V_f < V_i (compression) the sign of work done on the process is positive.

Question 50.
Derive the relation between ∆H and ∆U for an ideal gas. Explain each term involved in the equation.
Answer:
1. When the system at constant pressure undergoes changes from an initial state with H₁, U₁, V₁ and P parameters to a final state with H₂, U₂, V₂ and P parameters, the change in enthalpy ∆H, is given by
AH = U + PV

2. At initial state H₁ = U₁ + PV₁ ………(1)
At final state H₁ = U₁ + PV₁ ……..(2)
(2) – (1) ⇒ (H₂ – H₁) = (U₂ – U₁) + P(V₂ – V₁)
∆H = ∆U + P∆V …………(3)
Considering ∆U = q + w ; w = -P∆V
∆H = q + w + P∆V
∆H = q_p – P∆V+ P∆V
∆H = q_p …………(4)
q_p is the heat absorbed at constant pressure and is considered as heat content.

3. Consider a closed system of gases which are chemically reacting to produce product gases at constant temperature and pressure with V. and as the total volumes of the reactant and product gases respectively, and n1 and n_f are the number of moles of gaseous reactants
and products. Then,
For reactants: P V_i = n_i RT
For products: P V_f = n_f RT
Then considering reactants as initial state and products as final state,
P (V_i – V_i) = (n_i – n_i) RT
P∆V = ∆n_g RT
∆H = ∆U + P∆V
∆H = ∆U + ∆n_g RT ……….(5)

Question 51.
Suggest and explain an indirect method to calculate lattice enthalpy of sodium chloride crystal.
Answer:
The formation of NaCl can be considered in five steps. The sum of the enthalpy changes of these steps is equal to the enthalpy change for the overall reaction from which the lattice enthalpy of NaCl is calculated.
Let us calculate the lattice energy of sodium chloride using Bom-Haber cycle

∆H = heat of formation of sodium chloride = -411.3 kJmol^-1
∆H₁ = heat of sublimation of Na_(s) = 108.7 kJmol^-1
∆H₂ = ionisation energy of Na_(s) = 495. kJ mol^-1
∆H₃ = dissociation energy of Cl_2(g) = 244 kJ mol^-1
∆H₄ = Electron affinity of Cl_(g) = -349 kJ mol^-1
U = lattice energy of NaCl
∆H_f = ∆H₁ + ∆H₂ + ∆H₃ + ∆H₄ + U
∴ U = (∆H_f ) – (∆H₁ + ∆H₂ + \(\frac{1}{2}\)∆H₃ + ∆H₄)
=» U = (-411.3) – (108.7 + 495.0 + 122 – 349)
U = (-411.3) – (376.7)
∴ U = -788kJ mol^-1

Question 52.
List the characteristics of Gibbs free energy.
Answer:
Characteristics of Gibbs free energy:
1. Gibbs free energy is defined as the part of the total energy of a system that can be converted (or) available for conversion into work.
G = H – TS ………..(1)
Where
H = enthalpy, T = temperature and S = entropy

2. G is a state function and is a single value function.

3. G is an extensive property, whereas ∆G becomes intensive property for a closed system. Both G and ∆G values correspond to the system only.

4. ∆G gives criteria for spontaneity at constant pressure and temperature.

• If ∆G is negative (∆G < O), the process is spontaneous.
• If ∆G is positive (∆G > O), the process is non-spontaneous.
• If ∆G is zero (AG = O), the process is equilibrium.

5. For any system at constant pressure and temperature,
∆G = ∆H – T∆S ……….. (2)
We know AH = ∆U + P∆V
∆G = ∆U + P∆V – T∆S ………(3)

6. For the first law of thermodynamics, ∆U = q + w
∆G= q+ w+P∆V – T∆S …………(4)

For second law of thermodynamics, ∆S = \(\frac {q}{T}\)
∆G = q + w + P∆V – T\(\frac {q}{T}\)
∆G = w + P∆V …………(5)
∆G = – w – P∆V ……….(6)

7. – P∆V represent the work done due to expansion against constant external pressure. Therefore, it is clear that the decrease in free energy (-∆G) accompanying a process taking place at constant temperature and pressure is equal to the maximum work obtainable from the system other than the work of expansion.

8. Unit of Gibb’s free energy is J mol^-1

Question 53.
Calculate the work done when 2 moles of an ideal gas expands reversibly and isothermally from a volume of 500 ml to a volume of 2 L at 25°C and normal pressure.
Solution:
Given
n = 2 moles
V_i = 500 ml = 0.5 lit
V_f = 2 lit
T = 25°C = 298 K
w = -2303 nRTIog (\(\frac{V_{f}}{V_{i}}\))
w = -2.303 × 2 × 8.314 × 298 × log (4)
w = -2.303 × 2 × 8.314 × 298 × 0.6021
w = -6871 J
w = -6.871 kJ.

Question 54.
In a constant-volume calorimeter, 3.5 g of gas with molecular weight 28 was burnt in excess oxygen at 298 K. The temperature of the calorimeter was found to increase from 298 K to 298.45 K due to the combustion process. Given that the calorimeter constant is 2.5kJ K^-1. Calculate the enthalpy of combustion of the gas in kJ mol^-1.
Solution:
Given,
T_i = 298 K
T_f = 298.45 K
k = 2.5 kJ K
m = 3.5g
M_m = 28
heat evolved = k∆T
∆H_C = k (T_f – T_i)
∆H_C = 2.5 kJ K’ (298.45 – 298) K^-1
∆H_C = 1.125 kJ
∆H_C = \(\frac {1.125}{3.5}\) x 28 kJ mol^-1
∆H_C = 9 kJ mol^-1

Question 55.
Calculate the entropy change in the system, and surroundings, and the total entropy change in the universe during a process in which 245 J of heat flow out of the system at 77°C to the surrounding at 33°C.
Solution:
Given
T^sys = 77° C = (77 + 273) = 350 K
T^surr = 33°C = (33 + 273) = 360 K
q = 245J

∆S_sys = \(\frac{q}{T_{s y}}=\frac{-245}{350}\) = -0.7 JK^-1

∆S_surr = \(\frac{q}{T_{s \mathrm{sr}}}=\frac{+245}{306}\) = +0.8 JK^-1

∆S_univ = ∆S_sys + ∆S_surr

∆S_univ = -0.7 JK^-1 + 0.8 JK^-1

∆S_univ = 0.1 JK^-1

Question 56.
1 mole of an ideal gas, maintained at 4.1 atm and at a certain temperature, absorbs heat 3710/and expands to 2 liters. Calculate the entropy change in the expansion process.
Solution:
Given
n = 1 mole
P = 4.1 atm
V = 2 Lit
T = ?
q = 3710 J
∆S = \(\frac{q}{T}\)

∆S = \(\frac{q}{\frac{p v}{n R}}\)

∆S = \(\frac{n R q}{P V}\)

∆S = \(\frac{1 \times 0.082 \text { lit atm } K^{-1} \times 3710 J}{4.1 \text { atm } \times 2 \text { lit }}\)

∆S = 37.10 JK^-1

Question 57.
30.4 kJ is required to melt one mole of sodium chloride. The entropy change during melting is 28.4 JK^-1 mol^-1. Calculate the melting point of sodium chloride.
Answer:
Given,
∆H_f(NaCl) = 30.4 kJ = 30400 J mol^-1
∆S_f(NaCl) = 28.4 JK^-1 mol^-1
∆S^-1 = \(\frac{\Delta H_{f}}{T_{f}}\)

T_f = \(\frac{\Delta H_{f}}{\Delta S_{f}}\)

T_f = \(\frac{30400 J m o l^{-1}}{28.4 J K^{-1} m o l^{-1}}\)

T_f = 1070.4 K

Question 58.
Calculate the standard heat of formation of propane, if its heat of combustion is -2220.2 kJ mol^-1. The heats of formation of CO₂(g) and H₂O(1) are -393.5 and -285.8 kJ mol^-1 respectively.
Solution:
Given:
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
∆H°C = 2220.2kJ mol^-1 ……………..(1)
C + O₂ → CO₂
∆H°_f = -393.5 kf mol^-1 ……….(2)
H₂ + \(\frac{1}{2}\)O₂ → H₂O
∆H°_f = -285.8 kJ mol^-1 ……………(3)
3C + 4H₂ → C₃H₈
∆H°_c =?
(2) × (3)
⇒ 3C + 3O₂ → 3CO₂
∆H°_f = -1180.5 kJ ………..(4)
(3)× (4)
⇒ 4H₂ + 2O₂ → 4H₂O
∆H°_f = 1143.2 kJ ……..(5)
(4) + (5) – (1)
⇒ 3C + 3O₂ + 4H₂ + 2O₂ + 3CO₂ + 4H₂O → 3CO₂ + 4H₂O + C₃H₈ + 5O₂
∆H°_f = -1180.5 – 1143.2 – (-2220.2) kJ
3C + 4H₂ → C₃H₈
∆H°_f = -103.5 kJ
Standard heat of formation of propane is ∆H°_f(C3H8) = -103.5 kJ

Question 59.
You are given normal boiling points and standard enthalpies of vapourisation. Calculate the entropy of vapourisation of liquids listed below.

Answer:
For ethanol
Given:

Question 60.
For the reaction Ag₂O(s) → 2Ag(s)+12O₂(g) ∆H = 30.56 kJ mol^-1 and ∆S = 6.66JK^-1 mol^-1 (at 1 atm). Calculate the temperature at which G is equal to zero. Also predict the direction of the reaction (I) at this temperature and (ii) below this temperature.
Solution:
Given,
∆H = 30.56 kJ mol^-1
∆S = 6.66 x 10^-3 kJK^-1 mol^-1
T = ? at which ∆G =0
∆G = ∆H – T∆S
0 = ∆H – T∆S
T = \(\frac{\Delta H}{\Delta S}\)

T = \(\frac{30.56 \mathrm{~kJ} \mathrm{~mol}^{-1}}{66.6 \times 10^{-3} \mathrm{~kJ} K^{-1} \mathrm{~mol}^{-1}}\)
T = 4589 K

(i) At 4589K;
∆G = 0 the reaction is in equilibrium.
(ii) at temperature below 4598 K
∆H > T∆S
∆G = ∆H – T∆S > 0, the reaction in the forward direction, is non spontaneous. In other words the reaction occurs in the backward direction.

Question 61.
What is the equilibrium constant K_eq for the following reaction at 400K.
2NOCl(g) ⇌ 2NO(g) + Cl₂(g), given that ∆H° = 77.2 kJ mol^-1 ∆S° = 122 JK^-1 mol^-1
Answer:

Question 62.
Cyanamide (NH₂CN) is completely burnt in excess oxygen in a bomb calorimeter, ∆U was found to be -742.4 kJ mol^-1, calculate the enthalpy change of the reaction at 298K.
NH₂CN(s) + \(\frac{3}{2}\)O₂(g) → N₂(g) + CO₂(g) + H₂O (l) ∆H = ?
Solution:
Given,
T = 298K ; ∆U = -742.4 kJ mol^-1
∆H = ?
∆H = ∆U + ∆n_(g)RT
∆H = ∆U + (n_p – n_r) RT
∆H = – 742.4 +[2 – \(\frac {3}{2}\)] x 8.314 x 10^-3 x 298
∆H = -742.4 + (0.5 x 8.314 x 10^-3 x 298)
∆H = -742.4 + 1.24 .
∆H = -741.16 kJ mol^-1

Question 63.
Calculate the enthalpy of hydrogenation of ethylene from the following data. Bond energies of C – H, C – C, C = C and H – Hare 414, 347, 618 and 435 kJ mol^-1.
Solution:
Given
E_C-H= 414 kJ mol^-1
E_C-C= 347 kJ mol^-1
E_C-C= 6l8 kJ mol^-1
E_H-H = 435 kJ mol^-1

∆H_r = Σ(Bond energy)_r – Σ(Bond energy)_p
∆H_r = (E_C=C + 4E_C-H + E_H-H) – (E_C-C + 6E_C-H)
∆H_r = (618 + (4 × 414) + 315) – (347 + (6 ×414))
∆H_r = 2709 – 2831
∆H_r = -122 kJ mol^-1

Question 64.
Calculate the lattice energy of CaCl2 from the given data
Ca(s) + Cl₂(g) → CaCl₂(s) ∆H°_f = – 795 kJ mol^-1
Atomisation:
Ca(s) → Ca(g) ∆H°₁ = -795 kJ mol^-1

Ionisation:
Ca(g) → Ca²⁺(g) + 2e^-1
∆H°₂ = 2422 kJ mol^-1

Dissociation:
Cl₂(g) → 2Cl(g)
∆H°₃ = + 242.8 kJ mol^-1

Electron Affinity:
Cl(g) + e^– → Cl^-1
∆H°₄ = -355 kJ mol^-1
Answer:
∆H_f = ∆H₁ + ∆H₂ + ∆H₃+∆H₄ + u
-795 = 121 + 2422 + 242.8 + (2 × -355) + u
-795 = 2785.8 – 710 + u
-795 = 2075.8 + u
u = -795 – 2075.8
u = -2870.8 kJ mol^-1

Question 65.
Calculate the enthalpy change for the reaction Fe203 + 3C0 – 2Fe + 3C02 from the following data.
2Fe + \(\frac{3}{2}\)O₂ → Fe₂O₃; ∆H = -741 kJ
C + \(\frac{3}{2}\)O₂ → CO; ∆H=-137kJ
C + O₂ → CO2; ∆H = – 394.5 kJ
Answer:

Question 66.
When 1-pentyne (A) is treated with 4N alcoholic KOH at 175°C, it is converted slowly into an equilibrium mixture of 1.3% 1-pentyne(A), 95.2% 2-pentyne(B), and 3.5% of 1,2 pentadiene (C) the equilibrium was maintained at 175°C, calculate ∆G° for the following equilibria.
B ⇌ A; ∆G°₁ =?
B ⇌ C; ∆G°₂ =?
Solution:
T = 175°C = 175 + 273 = 448 K
Concentration of 1 – pentyne [A] = 1.3%
Concentration of 2 – pentyne [B] = 95.2%
Concentration of 1, 2 – pentadiene [C] = 3.5%
At equiLibrium
B ⇌ A
95.2% 1.3% ⇒ K₁ = \(\frac{3.5}{95.2}\) = 0.0 136
B ⇌ C
95.2% 3.5% ⇒ K₁ = \(\frac{1.3}{95.2}\) = 0.0367
⇒ ∆G₁° = -2.303 RT log K₁
∆G₁° = – 2.303 x 8.3 14 x 448 x log 0.0136
∆G₁° = + 16010 J
∆G₁° = + 16 kJ
⇒ ∆G₂°= – 2.303 RT log K₂
∆G₂° = -2.303 x 8.314 x 448 x log 0.0367
∆G₂° = + 12312 J
∆G₂° = +12.312 kJ.

Question 67.
At 33K, N₂O₄ is fifty percent dissociated. Calculate the standard free energy change at this temperature and at one atmosphere.
Solution:
Given
T= 33 K
N₂O₄ ⇌ 2NO₂
Initial concentration: 100%  0
Concentration dissociated 50% – Concentration remaining at equilibrium 50% 100%
K_eq = \(\frac{100}{50}\) = 2
∆G° = -2.303 RT log K_eq
∆G°= -2.303 × 8.314 × 33 × log 2
∆G° = -190.18 Jmol^-1

Question 68.
The standard enthalpies of formation of SO₂ and SO₃ are – 297 kJ mol^-1 and – 396 kJ mol^-1 respectively. Calculate the standard enthalpy of reaction for the reaction: SO +4-0 — SO
Solution:
Given,
∆G_f°(SO₂) = – 297 KJ mol^-1
∆G_f°(SO₂) = – 297 KJ mol^-1
SO₂ + \(\frac{1}{2}\)O₂ → SO₃ ∆H_r° = ?
∆H_r° = (∆H_f°)_compound – ∑(∆H_f°)_elements
∆H_r° = ∆H_f° (SO₃) – [∆H_f° (SO₂) + \(\frac{1}{2}\) ∆H_f° (O₂)]
∆H_r° = – 396 kJ mol^-1 – (- 297 kJ mol^-1 + 0)
∆H_r° = – 396 kJ mol^-1+297
∆H_r° = – 99 kJmol^-1

Question 69.
For the reaction at 298 K: 2A + B → C
∆H = 400 Jmol^-1; ∆S = 0.2 JK∆ mol^-1 Determine the temperature at which the reaction would be spontaneous.
Solution:
Given,
T = 298 ∆T
∆H = 400 J mol^-1 = 400 J mol^-1
∆S = 0.2 JK^-1 mol^-1
∆G = ∆H – T∆S
if T = 2000 K
∆G = 400 – (0.2 × 2000) = 0
if T > 2000 K
∆G will be negative. The reaction would be spontaneous only beyond 2000 K

Question 70.
Find out the value of equilibrium constant for the following reaction at 298K,
2NH₃ + CO₂ ⇌ NH₂CONH₂ (aq) + H₂O (l) Standard Gibbs energy change, ∆G°_r at the given temperature is -13.6 kJ mol^-1.
Solution:
Given:
T = 298 K
∆G°_r = -13.6 kJ mol^-1
= – 13600 J mol^-1
∆G° = – 2.303 RT log K_eq
log K_eq = \(\frac{-\Delta G^{0}}{2.303 R T}\)

log K_eq = \(\frac{13.6 \mathrm{~kJ} \mathrm{~mol}^{-1}}{2.303 \times 8.314 \times 10^{-3} \mathrm{JK}^{-1} \mathrm{~mol}^{-1} \times 298 \mathrm{~K}}\)

log K_eq = 2.38
K_eq = antilog (2.38)
K_eq = 239.88

Question 71.
A gas mixture of 3.67 lit of ethylene and methane on complete combustion at 25°C and at 1 atm pressure produces 6.11 lit of carbon dioxide. Find out the amount of heat evolved in kJ, during this combustion. (∆H_C(CH4)) = -890 kJmol^-1 and ∆H_C(C2H4) = -1423 kJ mol^-1
Solution:
Given
∆H_C(CH4) = – 890 kJ mol^-1
∆H_C(C2H4) = -1423 kJ mol^-1
Let the mixture contain x lit of CH₄ and (3.67 – x) lit of ethylene.
CH₄ + 2O₂ → CO + 2H₂O
x lit               x lit
C₂H₄ + 3O₂ → 2 CO₂ + 2H₂O
(3.67 -x) lit 2 (3.67 -x) lit
Volume of Carbondioxide formed = x + 2(3.67 – x) = 6.11 lit
x + 7.34 – 2x = 6.11
7.34 – x = 6.11
x = 1.23 lit
Given mixture contains 1.23 lit of methane and 2.44 lit of ethylene, hence

11th Chemistry Guide Thermodynamics Additional Questions and Answers

I. Choose the best answer:

Question 1.
When a liquid boils, there is ……….
(a) increase in entropy
(b) a decrease in entropy
(c) increase in heat of vaporization
(d) an increase in free energy
Answer:
(a) Increase in entropy

Question 2.
Which one of the following is a closed system?
(a) Hot water in a closed beaker
(b) Hot water in a thermos flask
(c) Hot water in an open beaker
(d) Chemical reactions
Answer:
(a) Hot water in a closed beaker

Question 3.
In which of the following process. the process is always non-feasible?
(a) ∆H >O, ∆S>O
(b) ∆H<O, ∆S>O
(c) ∆H >O, ∆S<O
(d) ∆H<O, ∆S>O
Answer:
(c) ∆H >O, ∆S<O

Question 4.
Which of the following is/are intensive properties?
1. refractive index
2. density
3. number of moles
4. molar volume
(a) 1, 2 and 4
(b) 1, 3 and 4
(c) 1, 2 and 3
(d) 2, 3 and 4
Answer:
(b) 1, 3 and 4

Question 5.
Which of the following process is feasible at all temperatures?
(a) ∆H>O.∆S>O
(b) ∆H>O.∆S<O
(c) ∆H<O.∆S>O
(d) ∆H<O.∆S<O
Answer:
(c) ∆H<O.∆S>O

Question 6.
Which of the following is/are state functions?
1. Pressure
2. work
3. internal energy
4. Free energy
5. heat
(a) 1, 2 and 4
(b) 1, 3 and 4
(e) 1, 2 and 3
(d)2, 3 and 4
Answer:
(b) 1, 3 and 4

Question 7.
Calculate the entropy change of a process H₂O_(l) → H₂O_(g) at 373K. Enthalpy of vaporization of water is 40850 J Mole^-1.
(a) 120 J K^-1 mol^-1
(b) 9.1 x 10 J K^-1 mol^-1
(c) 9.1 x 10 J K^-1 mol^-1
(d) 109.52 J K^-1 mol^-1
Answer:
(d) 109.52 J K^-1 mol^-1
Solution:
EnthaLpy of vaporization of water is = ∆H = 40850 J mol^-1
Boiling point = 373 K = T_b
∆S = \(\frac{\Delta \mathrm{H}}{\mathrm{T}_{\mathrm{b}}}\) = \(\frac{40850}{373}\) = 109.517 = 109.52 JK^-1  mol^-1

Question 8.
Which is correct about internal energy, U?
(a) It is an extensive property
(b) It is a state function
(c) For a cyclic process. ∆U = 0.
(d) Change in internal energy is ∆U = U_i – U_f
Answer:
(a) It is an extensive property

Question 9.
Work done by’ a given system with an ideal gas in a reversible process is w_rev =
(a) – nRln (V_f/V_i)
(b) – nRTln (V_i/V_f)
(c) – nRTln (V_f/V_i)
(d) – nTln (V_f/V_i)
Answer:
(c) – nRTln (V_f/V_i)

Question 10.
For a cyclic process involving isothermal expansion of an ideal gas
(a) ∆U = 0
(b) ∆U = q
(c) ∆U = q + w
(d) ∆U = q – w
Answer:
(a) ∆U = 0

Question 11.
Choose the correct statement about enthalpy
(a) Enthalpy is a path function
(b) Enthalpy change ∆H = ∆U + V∆P
(c) In an endothermic process, ∆H = 0.
(d) In an exothermic process. ∆H is negative
Answer:
(d) In an exothermic process. ∆H is negative

Question 12.
Which ofthc following reactions correctly indicates the process of atomization?
(a) CH₄ → CH₃(g) + H(g)
(b) CH₄(g) → CH(g) + 4H(g)
(c) CH(g) + O₂(g) → CO₂(g)
(d) N₂(g) + 3H₂(g) → 2NN₃(g)
Answer:
(b) CH₄(g) → CH(g) + 4H(g)

Question 13.
A reaction has both H and S negative. The rate of reaction
(a) increases with increase of temperature
(b) increases with decrease of temperature
(e) remains unaffected by change of temperature
(d) cannot be predicted for change in temperature
Answer:
(b) increases with decrease of temperature

Question 14.
Evaporation of water is
(a) an exothermic change
(b) an endothermic change
(e) a process where no heat changes occur
(d) a process accompanied by chemical reaction
Answer:
(b) an endothermic change

Question 15.
The entropy change for a non spontaneous reaction is 140 JK^-1 mol at 298 K. The reaction is
(a) reversible
(b) irreversible
(c) exothermic
(d) endothermic
Answer:
(d) endothermic

Question 16.
The enthalpy and entropy change for the reaction: Br₂(l) +Cl₂(g) → 2BrCl(g) are 30 kJ mol^-1 and 105 kJ mol^-1 respectively. The temperature at which the reaction will be in
equilibrium is
(a) 300 K
(b) 285.7 K
(c) 273 K
(d) 450 K
Answer:
(b) 285.7 K

Question 17.
Three moles ofan ideal gas expanded spontaneously into vaccum. The work done will be
(a) Infinite
(b) 3 JouIes
(c) 9 Joules
(d) zero
Answer:
(d) zero

Question 18.
If the enthalpy change for the transition of liquid water to steam is 30 kJ mol^-1 at 27°C, the entropy change for the process would be
(a) 10 J mol^-1K^-1
(b) 1.0 J mol^-1K^-1
(c) 0.1 J mol^-1K^-1
(d) 100 J mol^-1K^-1
Answer:
(d) 100 J mol^-1K^-1

Question 19.
Enthalpy change for the reaction,
4H(g) → 2H₂(g) is – 869.6 kJ
The dissociation energy of H-H bond is
(a) -434.8 kJ
(b) -869.6 kJ
(c) + 434.8 kJ
(d) +217.4 kJ
Answer:
(c) + 434.8 kJ

Question 20.
Which of the following will have the highest ∆H_vap Value?
(a) Acetone
(b) Ethanol
(c) Carbon tetrachloride
(d) Chloroform
Answer:
(b) Ethanol

Question 21.
The total entropy change for a system and its surroundings increases, if the process is
(a) reversible
(b) irreversible
(c) exothermic
(d) endothermic
Answer:
(b) irreversible

Question 22.
∆S is positive for the change
(a) mixing of two gases
(b) boiling of liquid
(c) melting of solid
(d) all of these
Answer:
(d) all of these

Question 23.
If w₁, w₂, w₃ and w₄ are work done in isothermal, adiabatic, isobaric and isochoric reversible processes, the correct order (for expansion) will be
(a) w₁ > w₂ > w₃ > w₄
(b) w₃ > w₂ > w₁ > w₄
(c) w₃ > w₂ > w₄ > w₁
(d) w₃ > w₁ > w₂ > w₄
Answer:
(d) w₃ > w₁ > w₂ > w₄

Question 24.
The enthalpy of vapourisation of a liquid is 30 kJ^-1 mol^-1 and the entropy of vaporization is 75 JK mol^-1 The boiling point of the liquid at 1 atm is ……….
(a) 250 K
(b) 400 K
(c) 450 K
(d) 600 K
Answer:
(b) 400 K
Solution:
∆H_vap = 30 kJ mol^-1 x 1000 = 30000 J mol^-1
∆S_vap = 75 J mol^-1
T_b = Boiling point = ?
∆S_vap = \(\frac{\Delta \mathrm{H}_{\mathrm{vap}}}{\mathrm{T}_{\mathrm{b}}}\)
∴ T_b = \(\frac{\Delta \mathrm{H}_{\mathrm{vap}}}{\Delta \mathrm{S}_{\mathrm{vap}}}\) = \(\frac {30000}{75}\) = 400K
T_b = 400 K
Tb = 400 K

Question 25.
A hydrogen bond is very useful in determining the structures and properties of compounds. Its energy varies between
(a) 12 – 20 kJ /mol
(b) 50 – 100 kJ/mol
(c) 10 – 100 kJ/mol
(d) 75 – 200 kJ/mol
Answer:
(c) 10 – 100 kJ/mol

Question 26.
In which of the enlisted cases, Hess’s law is not applicable?
(a) Determination of lattice energy
(b) Determination of resonance energy
(c) Determination of enthalpy of transformation of one allotropic form to another
(d) Determination of entropy
Answer:
(d) Determination of entropy

Question 27.
The amount of energy required to completely remove the constituent ions from its crystal lattice to an infinite distance is called
(a) lattice energy
(b) ionization energy
(c) internal energy
(d) free energy
Answer:
(a) lattice energy

Question 28.
Statement -1:
The allotropes of carbon, namely, graphite and diamond differ each other.
Statement -2:
They possess different internal energies and have different structures.
In the above statement/s
(a) 1 alone is correct
(b) 2 alone is correct
(c) both 1 and 2 are correct
(d) both 1 and 2 are incorrect
Answer:
(c) both 1 and 2 are correct

Question 29.
Which of the following statement is incorrect? According to thermodynamics, work
(a) is a path function
(b) appears only at the boundary of the system
(c) appears during the change in the state of the system.
(d) surroundings is so large that macroscopic changes occurs in the surroundings
Answer:
(d) surroundings is so large that macroscopic changes occurs in the surroundings

Question 30.
The work done by a force of one Newton through a displacement of one meter is called
(a) joule
(b) calorie
(c) erg
(d) tesla
Answer:
(a) joule

Question 31.
The enthalpy of neutralization of strong acid vs strong base is approximately equal to ________(in kJ).
(a) 57.32
(b) – 57.32
(c) 5.98
(d) – 5.98
Answer:
(b) – 57.32

Question 32.
The maximum efficiency of an automobile engine working between the temperatures 816°C and 21°C is
(a) 73 %
(b) 45%
(c) 67%
(d) 78%
Answer:
(b) 45%

Question 33.
A reaction that occurs under the given set of conditions without any external driving force is called a reaction.
(a) Reversible
(b) spontaneous
(c) irrversible
(d) cyclic
Answer:
(b) spontaneous

Question 34.
Which one of the following spontaneous reaction is endothermic?
(a) combustion of methane
(b) dissolution of ammonium nitrate
(c) acid-base neutralization reaction
(d) none of the above
Answer:
(b) dissolution of ammonium nitrate

Question 35.
The available energy in the system to do work is called
(a) Gibbs free energy
(b) internal energy
(c) potential energy
(d) kinetic energy
Answer:
(a) Gibbs free energy

Question 36.
Which one of the following is incorrect about Gibbs free energy?
(a) Extensive property
(b) path function
(c) ∆G < 0 for a spontaneous process (d) ∆G > 0 for a non-spontaneous process
Answer:
(b) path function

Question 37.
Match the following:

(A) Adiabatic	(i) dp = 0
(B) Isothermal	(ii) dV = 0
(C) Isobaric	(iii) dq = 0
(D) Isochoric	(iv) dT = 0

(a) A – iii, B – iv, C – i, D – ii
(b) A – ii, B – iv, C – iii, D – i
(c) A – iv, B – iii, C – i, D – ii
(d) A – i, B – iv, C – ii, D – iii
Answer:
(a) A – iii, B – iv, C – i, D – ii

Question 38.
For a cyclic process involving isothermal expansion of an ideal gas, q =
(a) 0
(b) P∆V
(c) w
(d) – w
Answer:
(d) – w

Question 39.
In Calorimeter, the expression used to calculate the amount of heat change in the process is
(a) C = qm∆T
(b) C = m/q∆T
(c) C = q/m∆T
(d) C = q∆T/m
Answer:
(c) C = q/m∆T

Question 40.
“It is impossible to transfer heat from a cold reservoir to a hot reservoir without doing some work”. This statement is given by
(a) Clausius
(b) Kelvin
(c) Gibbs
(d) Joule
Answer:
(a) Clausius

II. Very short question and answers (2 Marks):

Question 1.
What is the aim of the study of chemical thermodynamics?
Answer:
The main aim of the study of chemical thermodynamics is to learn

• Transformation of energy from one form into another form.
• Utilization of various forms of energies.
• Change in the properties of system produced by chemical or physical effects.

Question 2.
What is a homogeneous system? Give an example.
Answer:
A system is called homogeneous if the physical state of all its constituents is the same. Example: a mixture of gases.

Question 3.
What are the limitations of thermodynamics?
Answer:

• Thermodynamics suggests the feasibility of reaction but fails to suggest the rate of reaction. It is concerned only with the initial and the final states of the system. It is not concerned with the path by which the change occurs.
• It does not reveal the mechanism of a process.

Question 4.
Define irreversible process.
Answer:
The process in which the system and surrounding cannot be restored to the initial state from the final state is called an irreversible process. All the processes occurring in nature are irreversible processes.

Question 5.
Define standard entropy change.
Answer:
The absolute entropy of a substance at 298 K and one bar pressure is called the standard entropy S°.

Question 6.
What is Zeroth law of thermodynamics?
Answer:
The law states that’ If two systems are separately in thermal equilibrium with a third one, then they tends to be in thermal equilibrium with themselves’.

Question 7.
What is meant by open system? Give example.
Answer:

• A system which can exchange both matter and energy with its surroundings is called an open system.
• Hot water contained in an open beaker is an example for open system.
• In this system, both water vapour and heat is transferred to the surroundings through the imaginary boundary.
• All living things are open systems because they continuously exchange matter and energy with the surroundings.

Question 8.
Define the specific heat capacity of a system.
Answer:
The heat absorbed by one kilogram of a substance to raise its temperature by one Kelvin at a specified temperature.

Question 9.
What is a reversible process?
Answer:
The process in which the system and surrounding can be restored to the initial state from the final state without producing any changes in the thermodynamic properties of the universe is called a reversible process.

Question 10.
What is a thermodynamic process? Give two examples.
Answer:
The method of operation which can bring about a change in the system is called thermodynamic process.
Examples: Heating, Cooling, expansion.

Question 11.
Distinguish between state function and path function.
Answer:
A state function is a thermodynamic property of a system, which has a specific value for a given state and does not depend on the path by which the particular state is reached. A path function is a thermodynamic property of the system whose value depends on the path by which the system changes from its initial to final states.

Question 12.
Write any two characteristics of internal energy.
Answer:

1. The internal energy of a system is an extensive property.
2. The internal energy of a system is a state function.

Question 13.
Write the importance of internal energy.
Answer:
The internal energy possessed by a substance differentiates its physical structure. For example, the allotropes of carbon, namely, graphite C (graphite) and diamond C (diamond), differ from each other because they possess different internal energies and have different structures.

Question 14.
Write notes on heat.
Answer:
The heat (q) is regarded as an energy in transit across the boundary separating a system from its surrounding. Heat changes lead to temperature differences between system and surrounding. Heat is a path function.

Question 15.
Write the thermodynamic significance of work.
Answer:
The work

1. is a path function.
2. appears only at the boundary of the system.
3. appears during the change in the state of the system.
4. in thermodynamics, surroundings is so large that macroscopic changes to surroundings do not happen.

Question 16.
What is meant by pressure-volume work?
Answer:
In elementary thermodynamics the only type of work generally considered is the work done in expansion (or compression) of a gas. This is known as pressure-volume work, PV work or expansion work.

Question 17.
What is specific heat capacity of a system?
Answer:
The heat absorbed by one kilogram of a substance to raise its temperature by one Kelvin at a specified temperature is called specific heat capacity of a system.

Question 18.
Distinguish between Cv and Cp.
Answer:
The molar heat capacity at constant volume (Cv) is defined as the rate of change of internal energy with respect to temperature at constant volume. The molar heat capacity at constant pressure (Cp) can be defined as the rate of change of enthalpy with respect to temperature at constant pressure.

III. Short Question and Answers (3 Marks):

Question 1.
What is internal energy?
Answer:
The internal energy of a system is equal to the energy possessed by all its constituents namely atoms, ions and molecules. The total energy of all molecules in a system is equal to the sum of their translational energy (U_t), vibrational energy (U_v), rotational energy (U_r), bond energy (U_b), electronic energy (U_e) and energy due to molecular interactions (U_i).
Thus:
U = U_t + U_v + U_r + U_b + U_e + U_i
The total energy of all the molecules of the system is called internal energy.

Question 2.
Give applications of bomb calorimeter.
Answer:

1. Bomb calorimeter is used to determine the amount of heat released in combustion reaction.
2. It is used to determine the calorific value of food.
3. Bomb calorimeter is used in many industries such as metabolic study, food processing, explosive testing etc.

Question 3.
What is Molar heat of fusion?
Answer:
The molar heat of fusion is defined as “the change in enthalpy when one mole of a solid substance is converted into the liquid state at its melting point”.
For example, the heat of fusion of ice
H₂O(s) → H₂O(l)
∆H(fusion) = +5.98 kJ

Question 4.
Write any three statements of first law of thermodynamics.
Answer:

1. Whenever an energy of a particular type disappears, an equivalent amount of another type must be produced.
2. The total energy of a system and surrounding remains constant (or conserved)
3. “Energy can neither be created nor destroyed, but may be converted from one form to another”.

Question 5.
Describe the need for the second law of thermodynamics.
Answer:
From the first law of thermodynamics, the energy of the universe is conserved. Let us consider the following processes:
A glass of hot water over time loses heat energy to the surrounding and becqmes cold.
When you mix hydrochloric acid with sodium hydroxide, it forms sodium chloride and water with evolution of heat.

In both these processes, the total energy is conserved and are consistent with the first law of thermodynamics. However, the reverse process i.e. cold water becoming hot water by absorbing heat from surrounding on its own does not occur spontaneously even though the energy change involved in this process is also consistent with the first law. However, if the heat energy is supplied to cold water, then it will become hot. i.e. the change that does not occur spontaneously and an be driven by supplying energy.

Question 6.
Write notes on entropy statement of second law of thermodynamics.
Answer:
The second law of thermodynamics can be expressed in terms of entropy, i.e “the entropy of an isolated system increases during a spontaneous process”.
For an irreversible process such as spontaneous expansion of a gas,
S_total > 0
S_total > S_system + S_surrounding
i.e., S_universe > S_system + S_surrounding
For a reversible process such as melting of ice,
S_system = S_surrounding
S_universe = 0

IV. Long Question and Answers(5 Marks):

Question 1.
Explain steps to write thermochemical equations.
Answer:
A thermochemical equation is a balanced stoichiometric chemical equation that includes the enthalpy change (∆H). The following conventions are adopted in thermochemical equations:

1. The coefficients in a balanced thermochemical equation refer to number of moles of reactants and products involved in the reaction.
2. The enthalpy change of the reaction ∆Hr has to be specified with appropriate sign and unit.
3. When the chemical reaction is reversed, the value of ∆H is reversed in sign with the same magnitude.
4. The physical states (gas, liquid, aqueous, solid in brackets) of all species are important and must be specified in a thermochemical reaction, since ∆H depends on the physical state of reactants and products.
5. If the thermochemical equation is multiplied throughout by a number, the enthalpy change is also multiplied by the same number.
6. The negative sign of ∆H_r indicates that the reaction is exothermic and the positive sign of ∆H_r indicates an endothermic reaction.

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Chemistry Guide Pdf Chapter 4 Hydrogen Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Chemistry Solutions Chapter 4 Hydrogen

11th Chemistry Guide Hydrogen Text Book Back Questions and Answers

Textual Questions:

I. Choose the best answer:

Question 1.
Which of the following statements about hydrogen is incorrect?
(a) Hydrogen ion, H₃O⁺ exists freely in solution.
(b) Dihydrogen acts as a reducing agent.
(c) Hydrogen has three isotopes of which tritium is the most common.
(d) Hydrogen never acts as cation in ionic salts.
Answer:
(c) Hydrogen has three isotopes of which tritium is the most common.

Question 2.
Water gas is
(a) H₂O(g)
(b) CO + H₂O
(c) CO + H₂
(d) CO + N₂
Answer:
(c) CO + H₂

Question 3.
Which one of the following statements is incorrect with regard to ortho and para dihydrogen ?
(a) They are nuclear spin isomers
(b) Ortho isomer has zero nuclear spin whereas the para isomer has one nuclear spin
(c) The para isomer is favoured at low temperatures
(d) The thermal conductivity of the para isomer is 50% greater than that of the ortho isomer.
Answer:
(b) Ortho isomer has zero nuclear spin whereas the para isomer has one nuclear spin

Question 4.
Ionic hydrides are formed by
(a) halogens
(b) chalogens
(c) inert gases
(d) group one elements
Answer:
(d) group one elements

Question 5.
Tritium nucleus contains
(a) 1p + 0n
(b) 2p + 1n
(c) 1p + 2n
(d) none of these
Answer:
(c) 1p + 2n

Question 6.
Non-stoichiometric hydrides are formed by
(a) palladium, vanadium
(b) carbon, nickel
(c) manganese, lithium
(d) nitrogen, chlorine
Answer:
(b) carbon, nickel

Question 7.
Assertion:
Permanent hardness of water is removed by treatment with washing soda.
Reason:
Washing soda reacts with soluble calcium and magnesium chlorides and sulphates in hard water to form insoluble carbonates
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false
(d) Both assertion and reason are false
Answer:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.

Question 8.
If a body of a fish contains 1.2 g hydrogen in its total body mass, if all the hydrogen is replaced with deuterium then the increase in body weight of the fish will be
(a) 1.2 g
(b) 2.4 g
(c) 3.6 g
(d) \(\sqrt{4.8}\) g
Answer:
(a) 1.2 g

Question 9.
The hardness of water can be determined by volumetrically using the reagent
(a) sodium thiosulphate
(b) potassium permanganate
(c) hydrogen peroxide
(d) EDTA
Answer:
(d) EDTA

Question 10.
The cause of permanent hardness of water is due to
(a) Ca(HCO₃)²
(b) Mg(HCO₃)²
(c) CaCl₂
(d) MgCO₃
Answer:
(c) CaCl₂

Question 11.
Zeolite used to soften hardness of water is, hydrated
(a) Sodium aluminium silicate
(b) Calcium aluminium silicate
(c) Zinc aluminium borate
(d) Lithium aluminium hydride
Answer:
(a) Sodium aluminium silicate

Question 12.
A commercial sample of hydrogen peroxide marked as 100 volume H₂O₂, it means that
(a) 1 ml of H₂O₂ will give 100 ml O₂ at STP
(b) 1 L of H₂O₂ will give 100 ml O₂ at STP
(c) 1 L of H₂O₂ will give 22.4 L O₂
(d) 1 ml of H₂O2 will give 1 mole of O₂ at STP
Answer:
(a) 1 ml of H₂O₂ will give 100 ml O₂ at STP

Question 13.
When hydrogen peroxide is shaken with an acidified solution of potassium dichromate in presence of ether, the ethereal layer turns blue due to the formation of
(a) Cr₂O₃
(b) CrO₄^2-
(c) CrO(O₂)₂
(d) none of these
Answer:
(c) CrO(O₂)₂

Question 14.
For decolourisation of 1mole of acidified KMnO₄, the moles of H₂O₂ required is
(a) \(\frac{1}{2}\)

(b) \(\frac{3}{2}\)

(c) \(\frac{5}{2}\)

(d) \(\frac{7}{2}\)
Answer:
(c) \(\frac{5}{2}\)

Question 15.
Volume strength of 1.5 NH₂O₂ is
(a) 1.5
(b) 4.5
(c) 16.8
(d) 8.4
Answer:
(d) 8.4

Question 16.
The hybridisation of oxygen atom is H₂O and H₂O₂ are, respectively
(a) sp and sp³
(b) sp and sp
(c) sp and sp²
(d) sp³ and sp³
Answer:
(d) sp³ and sp³

Question 17.
The reaction H₃PO₂ + D₂O → H₂DPO₂ + HDO indicates that hypo-phosphorus acid is
(a) tribasic acid
(b) dibasic acid
(c) monobasic acid
(d) none of these
Answer:
(c) monobasic acid
Solution:
Hypophosphorous acid on reaction with D₂O, only one hydrogen is replaced by deuterium and hence it is monobasic.

Question 18.
In solid ice, the oxygen atom is surrounded by
(a) tetrahedrally by 4 hydrogen atoms
(b) octahedrally by 2 oxygen and 4 hydrogen atoms
(c) tetrahedrally by 2 hydrogen and 2 oxygen atoms
(d) octahedrally by 6 hydrogen atoms
Answer:
(a) tetrahedrally by 4 hydrogen atoms
Solution:

Question 19.
The type of H-bonding present in ortho nitrophenol and p-nitrophenol are respectively
(a) intermolecular H-bonding and intra molecular f H-bonding
(b) intramolecular H-bonding and intermolecular H-bonding
(c) intramolecular H – bonding and no H – bonding
(d) intramolecular H -bonding and intramolecular H-bonding
Answer:
(b) intramolecular H-bonding and intermolecular H-bonding
                         

Question 20.
Heavy water is used as
(a) the modulator in nuclear reactions
(b) coolant in nuclear reactions
(c) both (a) and (b)
(d) none of these
Answer:
(c) both (a) and (b)
Solution:
(c) Heavy water is used as a moderator as well as coolant in nuclear reactions.

Question 21.
Water is a
(a) basic oxide
(b) acidic oxide
(c) amphoteric oxide
(d) none of these
Answer:
(c) amphoteric oxide
Solution:
Water is an amphoteric oxide.

II. Write brief answer to the following questions:

Question 22.
Explain why hydrogen is not placed with the halogen in the periodic table.
Answer:

• Hydrogen resembles alkali metals as well as halogens.
• Hydrogen resembles more alkali metals than halogens.
• The electron affinity of hydrogen is much less than that of halogen atoms. Hence the tendency to form hydride ion is low compared to that of halogens.
• In most of its compounds hydrogen exists in a +1 oxidation state. Therefore it is reasonable to place the hydrogen in group 1 along with alkali metals as shown in the latest periodic table published by IUPAC.

Question 23.
A cube at 0°C is placed in some liquid water at 0°C, the ice cube sinks – Why?
Answer:
In ice, each atom is surrounded tetrahedrally by four water molecules through hydrogen bonds. That is, the presence of two hydrogen atoms and two lone pairs of electrons on oxygen atoms in each water molecule allows the formation of a three-dimensional structure.

This arrangement creates an open structure, which accounts for the lower density of ice compared with water at 0°C. While in liquid water, unlike ice where hydrogen bonding occurs over a long-range, the strong hydrogen bonding prevails only in a short-range and therefore the denser packing. Hence, the ice cube sinks in water.

Question 24.
Discuss the three types of Covalent hydrides.
Answer:

1. They are the compounds in which hydrogen is attached to another element by sharing electrons.
2. The most common examples of covalent hydrides are methane, ammonia, water, and hydrogen chloride.
3. Molecular hydrides of hydrogen are further classified into three categories,
   • Electron precise (CH₄, C₂ H₆, SiH₄, GeH₄ )
   • Electron-deficient (B₂ H₆ ) and
   • Electron-rich hydrides (NH₃ , H₂O)
4. Since most of the covalent hydrides consist of discrete, small molecules that have relatively weak intermolecular forces, they are generally gases or volatile liquids.

Question 25.
Predict which of the following hydrides is gas on a solid (a) HCl (b) NaH. Give your reason.
Answer:
Sodium hydride (NaH) is gas on a solid. NaH is prepared by direct reaction of hydrogen gas with liquid sodium and it has a NaCl crystal structure. It is a tendency of deprotonating in many organic reactions. NaH is used in fuel cells.

Question 26.
Write the expected formulas for the hydrides of 4th-period elements. What is the trend in the formulas? In what way the first two numbers of the series different from the others?
Answer:
The expected formulas for the hydrides of 4th-period elements MH₄ (electron precise). M₂H₆ (electron-deficient) and MH₃ (electron-rich).
The trend in the formula is

• Electron precise hydrides – CH₄ C₂H₆, SiH₄, GeH₄
• Electron deficient hydrides – B₂H₆
• Electron rich hydrides – NH₃, H₂O

The first two members of the series KH, CaH₂ are ionic hydrides whereas the other members of the series CH₄, C₂H₆, SiH₄, B₂H₆, NH₃ are covalent hydrides.

Question 27.
Write the chemical equation for the following reactions.
Answer:
(i) the reaction of hydrogen with tungsten (VI) oxide NO₃ on heating.
(ii) hydrogen gas and chlorine gas.
Answer:
(i) Hydrogen can be used to reduce metal oxide into metal. Hydrogen reduces tungsten(VI) oxide into tungsten.
WO₃ + 3H₂ → W + 3H₂O

(ii) Hydrogen reacts with chlorine at room temperature under light gives hydrogen chloride.
H_2(g) + Cl_2(g) → 2HCl_(g)

Question 28.
Complete the following chemical reactions and classify them into (a) hydrolysis (b) redox (c) hydration reactions.

1. KMnO₄ + H₂O₂ →
2. CrCl₃ + H₂O →
3. CaO + H₂O →

Answer:

1. 2KMnO₄ + 3H₂O₂ → 2MnO₂ + 2KOH + 3H₂O + 3O_2(g)
   This reaction is a redox reaction.
2. CrCl₃ + 6H₂O₂ → [Cr(H₂O)₆)] Cl₃
   This reaction is a hydration reaction.
3. CaO + H₂O → Ca(OH)₂
   This reaction is a hydrolysis reaction.

Question 29.
Hydrogen peroxide can function as an oxidizing agent as well as a reducing agent. Substantiate this statement with suitable examples.
Answer:
Hydrogen peroxide can act both as an oxidizing agent and a reducing agent. Oxidation is usually performed in an acidic medium while the reduction reactions are performed in a basic medium.

In acidic conditions:
H₂O₂ + 2H⁺ + 2e^– → 2H₂O (E° = +1.77 V)
For example
2FeSO₄ + H₂SO₄ + H₂O₂ → Fe₂(SO₄)₃ + 2H₂O

In basic conditions:
HO₂^– + OH^– → O₂ + H₂O + 2e^– (E° = + 0.08V)

For Example,
2 KMnO_4(aq) + 3H₂O_2(aq) → 2MnO₂ + 2KOH + 2H₂O + 3O₂(g)

Question 30.
Do you think that heavy water can be used for drinking purposes?
Answer:

• Heavy water (D₂O) contains a proton and a neutron. This makes deuterium about twice as heavy as protium, but it is not radioactive. So heavy water is not radioactive.
• If you drink heavy water, you don’t need to worry about radiation poisoning. But it is not completely safe to drink, because the biochemical reaction in our cells is affected by the difference in the mass of hydrogen atoms.
• If you drink an appreciable volume of heavy water, you might feel dizzy because of the density difference. It would change the density of the fluid in your inner ear. So it is unlikely to drink heavy water.

Question 31.
What is the water-gas shift reaction?
Answer:
The carbon monoxide of the water gas can be converted to carbon dioxide by mixing the gas mixture with more steam at 400°C and passed over a shift converter containing iron/copper catalyst. This reaction is called as water-gas shift reaction.
CO + H₂O → CO₂ + H₂
The CO₂ formed in the above process is absorbed in a solution of potassium carbonate.
CO₂ + K₂CO₃ + H₂O → 2KHCO₃

Question 32.
Justify the position of hydrogen in the periodic table?
Answer:
Hydrogen resembles alkali metals in the following aspects.

1. Electronic configuration 1s¹ as alkali metals have ns¹.
2. Hydrogen forms unipositive H+ ion like alkali metals Na⁺, K⁺.
3. Hydrogen form halides (HX), oxides (H₂O) peroxide (H₂O₂) like alkali metals (NaX. Na₂O, Na₂O₂).
4. Hydrogen also acts as a reducing agent like alkali metals. Hydrogen resembles halogens in the following aspects.
5. Hydrogen has a tendency to gain one electron to form hydride ion (H^–) as halogens to form halide ion. (X^–).
6. Comparing the properties of hydrogen with alkali metals and with halogens, we can conclude that hydrogen resembles more alkali metals. In most of the compounds, hydrogen exists in a +1 oxidation state.
7. Therefore, it is reasonable to place the hydrogen in group 1 along with alkali metals as shown in the latest periodic table published by IUPAC.

Question 33.
What are isotopes? Write the names of isotopes of hydrogen.
Answer:
Atoms of the same element having same atomic number and different mass number are called isotopes.
Hydrogen has three naturally occurring isotopes, viz., protium (₁H¹ or H), deuterium (₁H² or D) and tritium (₁H³ or T). Protium ₁H¹ is the predominant form (99.985 %) and it is the only isotope that does not contain a neutron. Deuterium, also known as heavy hydrogen, constitutes about 0.015 %. The third isotope, tritium is a radioactive isotope of hydrogen which occurs only in traces (~1 atom per 1018 hydrogen atoms). Due to the existence of these isotopes naturally occurring hydrogen exists as H₂, HD, D₂, HT, T₂, and DT.

Question 34.
Give the uses of heavy water.
Answer:

1. Heavy water is used as a moderator in nuclear reactors as it can lower the energies of fast-moving neutrons.
2. D₂O is commonly used as a tracer to study organic reaction mechanisms and the mechanism of metabolic reactions.
3. It is also used as a coolant in nuclear reactors as it absorbs the heat generated.

Question 35.
Explain the exchange reactions of deuterium.
Answer:
When compounds containing hydrogen are treated with D₂O, hydrogen undergoes an exchange for deuterium. This reaction is known as the exchange reaction of deuterium.
2NaOH + D₂O → 2NaOD + HOD

HCl + D₂O → DCl + HOD

NH₄Cl + 4D₂O → ND₄Cl + 4HOD

These exchange reactions are useful in determining the number of ionic hydrogens present in a given compound. For example, when D₂O is treated with hypo-phosphorus acid only one hydrogen atom is exchanged with deuterium. It indicates that it is a monobasic acid.
H₃PO₂ + D₂O → H₂DPO₂ + HDO
It is also used to prepare some deuterium compounds:

Al₄C₃ + 12D₂O → 4Al(OD)₃ + 3CD₄
CaC₂ + 2D₂O → Ca(OD)₂ + C₂D₂
Mg₃N₂ + 6D₂O → 3Mg(OD)₂ + 2ND₃
Ca₃P₂ + 6D₂O → 3Ca(OD)₂ + 2PD₃

Question 36.
How do you convert parahydrogen into ortho hydrogen?
Answer:
Para hydrogen can be converted into ortho hydrogen in the following ways:

• By treating with catalysts platinum or iron.
• Bypassing an electric discharge
• By heating > 800°C.
• By mixing with paramagnetic molecules such as O₂, NO, NO₂.
• By treating with nascent/atomic hydrogen.

Question 37.
Mention the uses of deuterium.
Answer:

1. Deuterium is used to prepare heavy water which is used as a moderator in nuclear reactors.
2. Deuterium exchange reactions are useful in determining the number of ionic hydrogens present in a given compound.
3. It is also used to prepare some deuterium compounds.

Question 38.
Explain the preparation of hydrogen using electrolysis.
Answer:
High purity of hydrogen (>99.9%) is obtained by the electrolysis of water containing traces of acid or alkali or electrolysis of an aqueous solution of sodium hydroxide or potassium hydroxide using a nickel anode and iron cathode. This process is not economical for large-scale production.
At anode : 2OH^– → H₂O + ½ O₂ + 2e^–
At cathode : 2H₂O + 2e^– → 2OH^– + H₂
Overall reaction : H₂O → H₂ + 14 O₂

Question 39.
A group-1 metal (A) which is present ¡n common salt reacts with (B) to give compound (C) in which hydrogen is present in -1 oxidation state. (B) on reaction with gas to give universal solvent (D). The compound (D) reacts with (A) to give (B), a strong base. Identify A, B, C, D, and E. Explain the reactions.
Answer:
The metal that belongs to Group-1 which is present in common salt is Sodium(A).
The metal reacts with (B) to give compound (C) in which hydrogen is present in a -1 oxidation state.
2Na + H₂ → 2NaH
Hence, the (B) is hydrogen, and (C) is sodium hydride. (B) on reaction with gas to give universal solvent (D).
H₂ + O₂ → 2NaOH
The universal solvent (D) is water. The compound (D) on reaction with (A) to give (E) which is a strong base.
H₂O + 2Na → 2NaOH
The Compound (E) is Sodium hydroxide.
A – Sodium (Na)
B – Hydrogen (H₂)
C – Sodium Hydride (NaH)
D – Water (H₂O)
E – Sodium hydroxide (NaOH)

Question 40.
An isotope of hydrogen (A) reacts with diatomic molecule of element which occupies group number 16 and period number 2 to give compound (B) is used as a moderatorin nuclear reaction. (A) adds on to a compound (C), which has the molecular formula C₃H₆ to give (D). Identify A, B, C and D.
Answer:
An isotope of hydrogen (A) reacts with diatomic molecule of element which occupies group number 16 and period number 2 to give compound (B) is used as a moderator in nuclear reaction.
2D₂ + O₂ → 2D₂O
The isotope of hydrogen is deuterium(A), diatomic element is oxygen and the compound (B) is heavy water.
(A) adds on to a compound (C), which has the molecular formula C₃H₆ to give (D).
CH₃ – CH = CH₂ + D₂ → CH₃ – CHD – CH₂D
(C)                                     (D)
The compound (C) is propene and (D) is 1, 2 deutropropane.
A – Deuterium (D₂)
B – Heavy water (D₂O)
C – Propene (CH₃ – CH = CH₂)
D – 1, 2 deutero propene (CH₃ – CHD – CH₂D)

Question 41.
NH₃ has an exceptionally high melting point and boiling point as compared to those of the hydrides of the remaining element of group 15- Explain.
Answer:
When a hydrogen atom is covalently bonded to a highly electronegative atom such as nitrogen, the bond is polarized. Due to this effect, the polarized hydrogen atom is able to form a weak electrostatic interaction with another electronegative atom present in the vicinity.

This interaction is called hydrogen bonding. Hence, NH₃ has an exceptionally high melting point and boiling point as compared to those of the hydrides of the remaining element of group 15 due to intermolecular hydrogen bonding.

Question 42.
Why interstitial hydrides have a lower density than the parent metal?
Answer:

• d block elements form metallic or interstitial hydrides, on heating with dihydrogen under pressure.
• Hydrogen atoms being small in size occupy some in the metallic lattice producing distortion without any change in its type.
• The densities of these hydrides are lower than those of metals from which they are formed since the crystal lattice expands due to the inclusion of dihydrogen.

Question 43.
How do you expect the metallic hydrides to be useful for hydrogen storage?
Answer:
Metallic hydrides are usually obtained by hydrogenation of metals and alloys in which hydrogen occupies the interstitial sites (voids). Most of the hydrides are non-stoichiometric with variable composition (TiH _{1.5 – 1.8} and PdH_{0.6 – 0.8}), some are relatively light, inexpensive, and thermally unstable which makes them useful for hydrogen storage applications.

Question 44.
Arrange NH₃, H₂O, and HF in the order of increasing magnitude of hydrogen bonding and explain the basis for your arrangement.
Answer:

• The increasing magnitude of hydrogen bonding among NH₃, H₂O, and HF is HF > H₂O > NH₃
• The extent of hydrogen bonding depends upon electronegativity and the number of hydrogen atoms available for bonding.
• Among N, F, and O the increasing order of their electronegativities are N < O, H₂O > NH₃.

Question 45.
Compare the structures of HO and HO.
Answer:
Both in gas-phase and liquid-phase, the molecule adopts a skew confirmation due to repulsive interaction of the OH bonds with lone-pairs of electrons on each oxygen atom. Indeed, it is the smallest molecule known to show hindered rotation about a single bond.

H₂O₂ has a non-polar structure. The molecular dimensions in the gas phase and solid phase differ as shown in the figure. Structurally, H₂O₂ is represented by the dihydroxyl formula in which the two OH-groups do not lie in the same plane.

One way of explaining the shape of hydrogen peroxide is that the hydrogen atoms would lie on the pages of a partly opened book, and the oxygen atoms along the spine. In the solid phase of the molecule, the dihedral angle reduces to 90.2° due to hydrogen bonding and the O-O-H angle expands from 94.8° to 101.9°. Water has a bent structure and the H-O-H bond angle is 104.5°.

11th Chemistry Guide Hydrogen Additional Questions and Answers

I. Choose the best Answer:

Question 1.
Which one of the following elements mostly present in the sun and the stars?
(a) Hydrogen
(b) Lithium
(c) Helium
(d) Beryllium
Answer:
(a) Hydrogen

Question 2.
Hydrogen has similarities with
(a) Alkali metals and halogens
(b) Alkaline earth metals and halogens
(c) Alkalimetals and noble gases
(d) Halogens and noble gases.
Answer:
(a) Alkali metals and halogens

Question 3.
At room temperature normal hydrogen consists of …………….
(a) 25% ortho form + 75% para form
(b) 50% ortho form + 50% para form
(c) 75% ortho form + 25% para form
(d) 60% ortho form + 40% para form
Answer:
(c) 75% ortho form + 25% para form

Question 4.
Ionization energy of hydrogen is (in kJ mol^-1)
(a) 377
(b) 520
(c) 1413
(d) 1314
Answer:
(d) 1314

Question 5.
Consider the following statements:
(i) In the ortho form of the hydrogen molecule, the nuclear spins are opposed to each other
(ii) The magnetic moment of para-hydrogen is twice that of ortho hydrogen
(iii) By passing an electric discharge, para-hydrogen can be converted into ortho hydrogen. Which of the above statement is/are not correct?
(a) (i) only
(b) (iii) only
(c) (i) and (ii)
(d) (ii) and (iii)
Answer:
(c) (i) and (ii)

Question 6.
The predominant isotope of hydrogen is
(a) deuterium
(b) protium
(c) tritium
(d) heavy hydrogen
Answer:
(b) protium

Question 7.
The magnetic moment of para-hydrogen is ……………
(a) one
(b) zero
(c) twice
(d) maximum
Answer:
(b) zero

Question 8.
The number of naturally occurring hydrogens due to the existence of isotopes is
(a) 6
(b) 5
(c) 4
(d) 3
Answer:
(a) 6

Question 9.
The half-life period of tritium is ……………..
(a) 123.3 year
(b) 12.33 years
(c) 1 year
(d) 1600 years
Answer:
(a) 12.33 years

Question 10.
The correct order of melting point of isotopes of hydrogen is
(a) H < D < T
(b) T < D < H
(c) H < T < D
(d) D < H < T
Answer:
(a) H < D < T

Question 11.
Which one of the following is used to study the movements of groundwater?
(a) Deuterium
(b) Protium
(c) Tritium
(d) HD
Answer:
(a) Deuterium

Question 12.
Which of the following statement is correct about ortho-para hydrogen?
(a) The magnetic moment of para-hydrogen is twice that of a proton.
(b) Ortho form is more stable than para form
(c) Ortho form can be catalytically converted into the para form using platinum.
(d) At room temperature, normal hydrogen consists of 75% para form.
Answer:
(b) Ortho form is more stable than para form

Question 13.
Which of the following is produced by the bombardment of neutrons with lithium?
(a) Deuterium
(b) Protium
(c) Tritium
(d) Beryllium
Answer:
(c) Tritium

Question 14.
During electrolysis of water containing traces of acid, hydrogen is liberated at
(a) cathode
(b) anode
(c) both anode and cathode
(d) none of the above
Answer:
(a) cathode

Question 15.
Which of the following mixture of gases is called water gas?
(a) CO_2(g)  + H_2(g)
(b) CO_2(g) + N_2(g)
(c) CO_(g) + H_2(g)
(d) N_2(g) + H_2(g)
Answer:
(c) CO_(g) + H_2(g)

Question 16.
The catalyst used in the water gas shift reaction is
(a) Copper
(b) Nickel
(c) Platinum
(d) Palladium
Answer:
(a) Copper

Question 17.
The products formed during the cracking long chain hydrocarbon C₆H₁₂ are
(a) CO₂ + H₂O
(b) CO + H₂
(c) C₆H₁₀ + H₂
(d) C₆H₆ + 3H₂
Answer:
(d) C₆H₆ + 3H₂

Question 18.
The percentage of heavy water in normal water is
(a) 1.6 × 10⁴
(b) 1.6 × 10^-4
(c) 1.6 × 10^-3
(d) 1.6 × 10²
Answer:
(b) 1.6 × 10^-4

Question 19.
Hydrogen combines with carbon monoxide in the presence of copper catalyst will synthesize
(a) Ethanol
(b) Methane
(c) Methanol
(d) Methanal
Answer:
(c) Methanol

Question 20.
Lithium Aluminium Hydride is
(a) [LiAlH₃]
(b) Li[Al₂H₄]
(c) Li[AlH₂]
(d) Li[AlH₄]
Answer:
(d) Li[AlH₄]

Question 21.
Deuterium oxide is called
(a) hard water
(b) soft water
(c) heavy water
(d) heavy hydrogen
Answer:
(c) heavy water

Question 22.
Ammonia is synthesized by ______ process.
(a) Haber’s
(b) Bergius
(c) Decon’s
(d) Solvay
Answer:
(b) Bergius

Question 23.
Which of the following process is important in the food industry?
(a) Dehydration
(b) Dehalogenation
(c) Hydrogenation
(d) Carboxylation
Answer:
(c) Hydrogenation

Question 24.
The high melting and boiling points of water is due to
(a) Covalent bonding
(b) Hydrogen bonding
(c) Ionic bonding
(d) co-ordinate bonding
Answer:
(b) Hydrogen bonding

Question 25.
Which of the following is used for cutting and welding?
(a) Atomic hydrogen and oxy-hydrogen torches
(b) Liquid hydrogen
(c) Calcium hydride
(d) Sodium boro hydride
Answer:
(a) Atomic hydrogen and oxy-hydrogen torches

Question 26.
Water is an ______ oxide.
(a) acidic
(b) basic
(c) amphoteric
(d) neutral
Answer:
(a) acidic

Question 27.
Which one of the following is a universal solvent?
(a) Alcohol
(b) Ether
(c) CCl₄
(d) Water
Answer:
(d) Water

Question 28.
In CuSO₄.5H₂O, the number of water molecules forms co-ordinate bonds is
(a) 4
(b) 5
(c) 3
(d) 1
Answer:
(a) 4

Question 29.
Water does not react with
(a) Sodium
(b) Magnesium
(c) Beryllium
(d) Calcium
Answer:
(c) Beryllium

Question 30.
The number of water molecules in a hydrated crystal of Chromium chloride salt is
(a) 5
(b) 6
(c) 4
(d) 3
Answer:
(b) 6

Question 31.
Which set of metals does not have any effect on water?
(a) Ag, Au, Pt
(b) Na, Mg, Al
(c) Fe, Ca, Zn
(d) Fe, Pb, Na
Answer:
(a) Ag, Au, Pt

Question 32.
Temporary hardness of water is removed by ______ method.
(a) Dewar
(b) Clark’s
(c) Leibeg
(d) Haber
Answer:
(b) Clark’s

Question 33.
Consider the following statements.
(i) Silver, Gold, Mercury, and Platinum do not have any effect on water.
(ii) Carbon, Sulphur, and Phosphorous do not react with water.
(iii) Beryllium reacts with waterlessness violently.
Which of the following statements is/are not correct?
(a) (i) only
(b) (ii) and (iii)
(c) (iii) only
(d) (ii) only
Answer:
(c) (iii) only

Question 34.
The ion exchange bed used for the softening of hard water is
(a) Borates
(b) Zeolites
(c) Fluorides
(d) Phosphates
Answer:
(b) Zeolites

Question 35.
Water is an/a oxide.
(a) neutral
(b) acidic
(c) basic
(d) amphoteric
Answer:
(d) amphoteric

Question 36.
________ reactions are useful in determining the number of ionic hydrogens present in a given compound.
(a) Oxygen exchange
(b) Metal exchange
(c) Deuterium exchange
(d) Deuterium decomposition
Answer:
(c) Deuterium exchange

Question 37.
Which one of the following is used as water softener?
(a) Zeolites
(b) lime
(c) washing soda
(d) bleaching powder
Answer:
(a) Zeolites

Question 38.
Autoxidation of 2-alkyl anthraquinol gives
(a) Hydrogen peroxide
(b) Heavy water
(c) Hydrogen
(d) Water
Answer:
(a) Hydrogen peroxide

Question 39.
Which of the following is used to remove toxic and heavy metals from water?
(a) zeolites
(b) magnesia
(c) Bleaching agent
(d) lime
Answer:
(a) zeolites

Question 40.
Hydrogen peroxide solutions are stored in ______ container
(a) glass
(b) alkali metal
(c) plastic
(d) wooden
Answer:
(c) plastic

Question 41.
Consider the following statements.
(i) H₂O₂ is a powerful oxidising agent.
(ii) H₂O₂ is stored in dark coloured bottles
(iii) H₂O₂ is used as a moderator in nuclear reactors.
Which of the above statements is/are not correct.
(a) (i) only
(b) (i) and (ii)
(c) (iii) only
(d) (i), (ii) and (iii)
Answer:
(c) (iii) only

Question 42.
Disproportionation of hydrogen peroxide gives
(a) oxygen and hydrogen
(b) hydrogen and water
(c) hydrogen and ozone
(d) oxygen and water
Answer:
(d) oxygen and water

Question 43.
Which one of the following is prepared in the industry by the auto-oxidation of 2-alkylanthraquional?
(a) Heavy water
(b) Deuterium
(c) Hydrogen peroxide
(d) Tritium
Answer:
(c) Hydrogen peroxide

Question 44.
White pigment is
(a) Pb²(OH)₂(C0₃)₃
(b) Pb₃(OH)₂(C0₃)₂
(c) Pb₃(OH)(CO₃)₂
(d) Pb₂(OH)(CO₃)₃
Answer:
(b) Pb₃(OH)₂(C0₃)₂

Question 45.
Which one of the following is an electron-deficient hydride?
(a) C₂H₆
(b) B₂H₆
(c) GeH₄
(d) CH₄
Answer:
(b) B₂H₆

Question 46.
Compounds in which hydrogen is attached to another element by sharing of electrons are called _________ hydrides.
(a) Interstitial
(b) Molecular
(c) Saline
(d) Metallic
Answer:
(b) Molecular

Question 47.
Which one of the following is not a covalent hydride?
(a) Ammonia
(b) Methane
(c) Lithium hydride
(d) water
Answer:
(e) Lithium hydride

Question 48.
Each water molecule is linked to ______ other molecules through hydrogen bonds.
(a) five
(b) four
(c) six
(d) two
Answer:
(b) four

Question 49.
Which one of the following is used for hydrogen storage applications?
(a) Saline hydrides
(b) Interstitial hydrides
(c) covalent hydrides
(d) molecular hydrides
Answer:
(b) Interstitial hydrides

Question 50.
Hypo-phosphorus is a ______ acid.
(a) dibasic
(b) tribasic
(c) monobasic
(d) tetrabasic
Answer:
(c) monobasic

II. Very Short Question and Answers (2 Marks):

Question 1.
What are the isotopes of hydrogen?
Answer:
Hydrogen has three naturally occurring isotopes, viz., protium (₁H¹ or H), deuterium (₁H² or D) and tritium (₁H³ or T).

Question 2.
What is the nuclear reaction that takes place in the sun and other stars?
Answer:
The sun and other stars are composed mainly of 85 – 95% hydrogen which generates their energy by nuclear fusion of hydrogen nuclei into helium.

Question 3.
How is tritium prepared?
Answer:
Tritium is artificially prepared by bombarding lithium with slow neutrons in a nuclear fission reactor. The nuclear transmutation reaction for this process is as follows.
\({ }_{3}^{6} L i\) + \({ }_{0}^{1} n\) → \({ }_{2}^{4} \mathrm{He}\) + \({ }_{1}^{3} T\)

Question 4.
What are ortho and para hydrogens?
Answer:
In the hydrogen atom, the nucleus has a spin. When molecular hydrogen is formed, the spins of two hydrogen nuclei can be in the same direction or in the opposite direction as shown in the figure. These two forms of hydrogen molecules are called ortho and para hydrogens respectively.

Question 5.
Write the different forms of naturally occurring hydrogen?
Answer:
Due to the existence of three isotopes of hydrogen, Protium (H), Deuterium (D) and Tritium(T), naturally occurring hydrogen exists as H₂, HD, D₂, HT, T₂, and DT.

Question 6.
Why hydrogen gas is used as fuel?
Answer:
Hydrogen burns in the air, virtually free from pollution, and produces a significant amount of energy. This reaction is used in fuel cells to generate electricity.
2H_2(g) + O_2(g) → 2H₂O_(l) + energy

Question 7.
How is pure hydrogen prepared?
Answer:
High purity hydrogen (> 99.9 %) is obtained by the electrolysis of water containing traces of acid or alkali or the electrolysis of an aqueous solution of sodium hydroxide or potassium hydroxide using a nickel anode and iron cathode. However, this process is not economical for large-scale production.
At anode:
2OH^– → H₂O + \(\frac{1}{2}\)O₂ + 2e^–

At cathode:
2H₂O + 2e^– → 2OH^– + H₂

Overall reaction:
H₂O → H₂ + \(\frac{1}{2}\)O₂

Question 8.

how ¡s methanol synthesized from hydrogen? Give the uses of methanol.
Answer:

• Huge quantities of hydrogen are used for the synthesis of methanol from carbon monoxide in presence of a copper catalyst.
  CO_(g) + 2H_2(g) → CH₃OH_(l)
•  Methanol is an industrial solvent and a starting material for the manufacture of formaldehyde used in making plastics.

How is hydrogen prepared by steam reforming reaction?
Answer:
Hydrogen is produced on large scale by steam-reforming of hydrocarbons. In this method, a hydrocarbon such as methane is mixed with steam and passed over a nickel catalyst in the range 800- 900°C and 35 atm pressure.
CH₄ + H₂O → CO + 3H₂

Question 9.
What is water gas? How is it prepared?
Answer:
The mixture of carbon monoxide and hydrogen is called water gas. When steam is passed over a red-hot coke to produce carbon monoxide and hydrogen. The mixture of gases produced in this way is known as water gas (CO + H₂).
C + H₂O → (CO + H₂)Water gas /Syngas

Question 10.
How is hydrogen used in metallurgy? Prove it with an example.
Answer:
In metallurgy, for the extraction of pure metals from their mineral sources, hydrogen is used to reduce many metal oxides to metals at high temperatures.
CuO_(s) +H_2(g) → Cu_(s) +H₍₂₎O_(g)

Question 11.
How is Deuterium prepared?
Answer:
Normal water contains 1.6 × 10^-4 percentage of heavy water. The dissociation of protium water (H₂O) is more than heavy water (D₂O). Therefore, when water is electrolysed, hydrogen is liberated much faster than D₂. The electrolysis is continued until the resulting solution becomes enriched in heavy water. Further electrolysis of the heavy water gives deuterium.

Question 12.
What happens when steam is passed over red hot iron?
Answer:
When steam is passed over a red hot iron, the iron oxide will be formed with the release of hydrogen.
3Fe_(s) + 4H₂O_(l) → Fe₃O + 4H_4(g)

Question 13.
Write the physical properties of hydrogen.
Answer:
Hydrogen is a colorless, odorless, tasteless, lightest, and highly flammable gas. It is a non-polar diatomic molecule. It can be liquefied under low temperature and high pressure. Hydrogen is a good reducing agent.

Question 14.
What is the temporary hardness of water? How is it removed?
Answer:
Temporary hardness of water is due to the presence of soluble bicarbonates of magnesium and calcium. By heating/boiling, these salts decomposed into insoluble carbonate and hydroxide, respectively. The resulting precipitates can be removed by filtration.
Ca (HCO₃)_2(aq) → CaCO_3(s) + H₂O_(l) + CO_2(l)
Mg(HCO₃)_2(aq) → Mg(OH)_2(s) + CO_2(g)

Question 15.
Write the physical properties of water.
Answer:
Water is a colourless and volatile liquid. The peculiar properties of water in the condensed phases are due to the presence of inter molecular hydrogen bonding between water molecules. Hydrogen bonding is responsible for the high melting and boiling points of water.

Question 16.
How would you prepare Hydrogen peroxide?
Answer:
Hydrogen peroxide can be prepared by adding a metal peroxide to dilute acid.
BaO_2(s)+ H₂SO_4(aq) → BaSO_4(s) + H₃O_2(aq)

Question 17.
What is hard water? Give its types.
Answer:
Hard water contains high amounts of mineral ions. The most common ions found in hard water are the soluble metal cations such as magnesium & calcium, though iron, aluminium, and manganese may also be found in certain areas. The presence of these metal salts in the form of bicarbonate, chloride, and sulphate in water makes water ‘hard’.

Question 18.
What is meant by the temporary hardness of water?
Answer:
Temporary hardness is primarily due to the presence of soluble bicarbonates of magnesium and calcium.

Question 19.
Why the bond angle in the solid phase of H₂O₂ is reduced when compared to the gas phase of H₂O₂?
Answer:
Both the gas phase and solid phase, H₂O₂ adopt a skew configuration due to the repulsive interaction of the OH bonds with lone pairs of electrons on each oxygen atom. Indeed, it is the smallest molecule known to show hindered rotation about a single bond. In the solid phase, the dihedral angle is sensitive and hydrogen bonding decreases from 111.50 in the gas phase to 90.2 in the solid phase.

Question 20.
What are zeolites? Give its use.
Answer:
Zeolites are hydrated sodium alumino-silicates with a general formula, NaO.Al₂O₃ .xSiO₂ .yH₂O (x = 2 to 10, y = 2 to 6). Zeolites have a porous structure in which the monovalent sodium ions are loosely held and can be exchanged with hardness-producing metal ions (M = Ca or Mg) in water.

Question 21.
Prove that Hydrogen peroxide is a vigorous oxidizing agent and the solution of H₂O₂ is slightly acidic.
Answer:
H₂ O_2(aq) + 2 H₂O_(l) ⇌ H₃ O⁺_(aq) + HO⁺_2(aq)

H₃O⁺ Hydronium ion formation proves that solution of H₂O₂ is acidic. Because it donates H⁺ to H₂O to form H₃O⁺ ion.
H₂O₂ oxidizes Ferrous sulphate to Ferric sulphate in an acidic medium.
2FeSO_4(aq) + H₂SO_4(aq) + H₄O_2(aq) ⇌ Fe₂(SO₄)_3(aq)( + 2H₂O_(l)

Question 22.
What is the effect of shielding on ionization energy?
Answer:
As we move down a group, the number of inner shell electron increases which in turn increases the repulsive force exerted by them on the valence electrons, i.e., the increased shielding effect caused by the inner electrons decreases the attractive force acting the valence electron by the nucleus. Therefore, the ionization energy decreases.

Question 23.
What are ternary hydrides? Give example?
Answer:
Ternary hydrides are compounds in which the molecule is constituted by hydrogen and two types of elements, e.g., LiBH₄ or LiAlH₄.

Question 24.
How is hydrogen peroxide prepared?
Answer:
It can be prepared by treating metal peroxide with dilute acid.
BaO₂ + H₂SO₄ → BaSO₄ + H₂O₂

Na₂O₂ + H₂SO₂ → Na₂SO₄ + H₂O₂

Question 25.
What are hydrides? How are they classified?
Answer:
Hydrogen forms binary compounds with many electropositive elements including metals and non¬metals are called hydrides. It also forms ternary hydrides with two metals. E.g., LiBH₄ and LiAlH₄. The hydrides are classified as ionic, covalent and metallic hydrides according to the nature of bonding.

Question 26.
Write a note about gas hydrates.
Answer:
Gas hydrates are a kind of inclusion compound, where gas molecules are trapped in the crystal lattice having voids of the right size, without being chemically bonded. An interesting hydrate is that of the hydronium ion (H₂O) in the gas phase, similar to methane hydrate. Each water molecule is bonded to three others in the dodecahedron.

Question 27.
What are intra and inter-molecular hydrogen bonding?
Answer:
Hydrogen bonds can occur within a molecule is called intramolecular hydrogen bonding whereas between two molecules of the same type or different type is called intermolecular hydrogen bonding.

III. Short Questions and Answers (3 Marks):

Question 1.
Write notes on water-gas shift reaction?
Answer:
The carbon monoxide of the water gas can be converted to carbon dioxide by mixing the gas mixture with more steam at 400°C and passed over a shift converter containing iron/copper catalyst. This reaction is called as water-gas shift reaction.
CO + H₂O → CO₂ + H₂

The CO₄ formed in the above process is absorbed in a solution of potassium carbonate.
CO₂ + K₂CO₃ + H₂O → 2KHCO₃

Question 2.
Can we use concentrated sulphuric acid and pure zinc in the preparation of dihydrogen?
Answer:
Cone. H₂SO₄ cannot be used because it acts as an oxidizing agent also and gets reduced to SO₂
Zn + 2H₂SO₄ (Conc.) → ZnSO₄ + 2H₂O + SO₂
Pure Zn is not used because it is non-porous and the reaction will be slow. The impurities in Zn help in the constitute the electrochemical couple and speed up the reaction.

Question 3.
Write notes on isotopes of hydrogen.
Answer:
Hydrogen has three naturally occurring isotopes, viz., protium (₁H¹ or H), deuterium (₁H² or D) and tritium (₁H³ or T). Protium (₁H¹) is the predominant form (99.985 %) and it is the only isotope that does not contain a neutron.
Deuterium, also known as heavy hydrogen, constitutes about 0.015%. The third isotope, tritium is a radioactive isotope of hydrogen which occurs only in traces (~1 atom per 1018 hydrogen atoms). Due to the existence of these isotopes naturally occurring hydrogen exists as H₂, HD, D₂, HT, T₂, and DT.

Question 4.
What are ortho and para hydrogen? How will you convert one form into another?
Answer:
In the hydrogen atom, the nucleus has a spin. When molecular hydrogen is formed, the spins of two hydrogen nuclei can be in the same direction or in the opposite direction as shown in the figure. These two forms of hydrogen molecules are called ortho and para hydrogens respectively.

At room temperature, normal hydrogen consists of about 75% ortho-form and 25% para-form. As the ortho-form is more stable than para-form, the conversion of one isomer into the other is a slow process. However, the equilibrium shifts in favour of para hydrogen when the temperature is lowered.

The para-form can be catalytically transformed into ortho-form using platinum or iron. Alternatively, it can also be converted by passing an electric discharge, heating above 800°C and mixing with paramagnetic molecules such as O₂, NO, NO₂ or with nascent/atomic hydrogen.

Question 5.
Discuss the methods of preparation of hydrogen.
Answer:
High purity hydrogen (> 99.9%) is obtained by the electrolysis of water containing traces of acid or alkali or the electrolysis of an aqueous solution of sodium hydroxide or potassium hydroxide using a nickel anode and iron cathode. However, this process is not economical for large-scale production.
At Anode:
2OH^– → H₂O + \(\frac{1}{2}\)O₂ + 2e^–

At Cathode:
2H₂O + 2e^– → 2OH^– + H₂

Overall Reaction:
H₂O → H₂ + \(\frac{1}{2}\)O₂
Hydrogen is conveniently prepared in the laboratory by the reaction of metals, such as zinc, iron, tin with dilute acid.
Zn + 2HCl → ZnCl₂ + H₂↑

Laboratory preparation of Hydrogen

Question 6.
Write the chemical reactions to show the amphoteric nature of water.
Answer:
Water is amphoteric in nature and it behaves both as an acid as well as the base. With acids stronger than themselves (e.g., H₂S) it behaves as a base, and with bases stronger than themselves (e.g., NH₃) it acts as an acid.

1. As a base : H₂O_(l) + H₂S_(aq) → H₃ O_(aq) + HS^–_(aq)
2. As an acid : H₂O_(l) + NH_3(aq) → OH^–_(aq) + NH⁺_4(aq)

Question 7.
Write the reaction of halogens with water.
Answer:
The halogens react with water to give an acidic solution. For example, chlorine forms hydrochloric acid and hypo chlorous acid. It is responsible for the antibacterial action of chlorine water, and for its use as bleach.
Cl₂ + H₂O → HCl + HOCl
Fluorine reacts differently to liberate oxygen from water.
2F₂ + 2H₂O → 4HF + O₂

Question 8.
Discuss the nature of hydrated salts with suitable examples.
Answer:
Many salts crystallized from aqueous solutions form hydrated crystals. The water in the hydrated salts may form a co-ordinate bond or just present in interstitial positions of crystals.
Examples: Cr(H₂O₆₎ Cl₃₎ – All six water molecules form a coordinate bond. BaCl_2.2H₂O – Both the water molecules are present in interstitial positions.
CuSO₄ .5H₂O – In this compound four water molecules form co-ordinate bonds while the fifth water molecule, present outside the coordination, can form an intermolecular hydrogen bond with another molecule. [Cu(H₂O)₄]SO₄. H₂O.

Question 9.
Distinguish between Hard water and Soft water.
Answer:
Hard water:

• The presence of magnesium and calcium in the form of bicarbonate, chloride, and sulfate in water makes hard water.
• The cleaning capacity of soap is reduced when used in hard water.
• When hard water is boiled deposits of insoluble carbonates of magnesium and calcium are obtained.

Soft water:

• The presence of soluble salts of calcium and magnesium in water makes it soft water.
• The cleaning capacity of soap is more when used in soft water.
• When soft water is boiled, there is no deposition of salts.

Question 10.
How is the temporary hardness of water removed by Clark’s method?
Answer:
In Clark’s method, the calculated amount of lime is added to hard water containing magnesium and calcium, and the resulting carbonates and hydroxides can be filtered off.
Ca(HCO₃)₂ + Ca(OH)₂ → 2CaCO₃ + 2H₂O
Mg(HCO₃) + 2Ca(OH)₂ → 2CaCO₃+ Mg(OH)₂ + 2H₂O

Question 11.
Describe ion exchange method of softening water (or) Explain Zeolite (or) Permutit process.
Answer:

1. Hardness can be removed by passing through an ion-exchange bed like zeolites or resin-containing column. Thus, the zeolites work as a water softeners.
2. Zeolites are hydrated sodium alumini-silicates with a general formula, NaO.Al₂O₃.xSiO₂.yH₂O (x = 2 – 10, y = 2 – 6). They have high ion exchange capacity.
3. The complex structure can represent Na₂ – Z with sodium as exchangeable cations. This method is called zeolite or permit process.
4. Zeolites have a porous structure in which the monovalent sodium ions are loosely held and can be exchanged with hardness producing divalent metal ions (Ca or Mg) in water.
   Na₂ – Z_(s) + M²⁺_(aq) → M-Z_(s) + 2Na⁺_(aq)
5. When exhausted, the materials can be regenerated by treating them with aqueous sodium chloride. Hard minerals caught in the zeolite are released and they get replenished with sodium ions.
   M-Z_(s) + 2NaCl_(aq) → Na_(s)-Z_(s) + MCl_2(aq)

Question 12.
Write the uses of heavy water.
Answer:

1. Heavy water is widely used as a moderator in nuclear reactors as it can lower the energies of fast neutrons
2. It is commonly used as a tracer to study organic reaction mechanisms and mechanism of metabolic reactions
3. It is also used as a coolant in nuclear reactors as it absorbs the heat generated.

Question 13.
What are metallic hydrides? Explain about it.
Answer:

• Metallic hydrides are obtained by hydrogenation of metals and alloys in which hydrogen occupies the interstitial sites (voids). Hence, they are called interstitial hydrides.
• The hydrides show properties similar to parent metals and hence they are also known as metallic hydrides.
• They arc mostly non-stoichiometric with variable composition (TiH_1.5-1.818 and PdH_0.6-0.8).
• Some are relatively light, inexpensive, and thermally unstable which makes them useful for hydrogen storage applications. Example, TiH₂, ZrH₂, ZnH₂.

IV. Long Question and Answers (5 Marks):

Question 1.
Justify the position of hydrogen in the periodic table.
Answer:
The hydrogen has the electronic configuration of 1s¹ which resembles with ns¹ general valence shell configuration of alkali metals and shows similarity with them as follows:
(i) It forms unipositive ion (H⁺) like alkali metals (Na⁺, K⁺, Cs⁺)
(ii) It forms halides (HX), oxides (H₂O), peroxides (H₂O₂) and sulphides (H₂S) like alkali metals (NaX, Na₂O, Na₂O₂, Na₂S)
(iii) It also acts as a reducing agent.

However, unlike alkali metals which have ionization energy ranging from 377 to 520 kJ mol^-1, the hydrogen has 1,314kJ mol^-1 which is much higher than alkali metals.

Like the formation of halides (X^–) from halogens, hydrogen also has a tendency to gain one electron to form hydride ion (H^–) whose electronic configuration is similar to the noble gas, helium. However, the electron affinity of hydrogen is much less than that of halogen atoms. Hence, the tendency of hydrogen to form hydride ion is low compared to that of halogens to form the halide ions as evident from the following reactions:

\(\frac{1}{2}\) H₂ + e^– → H^–                                 ∆H = + 36 kcalmol^-1
\(\frac{1}{2}\) Br₂ + e^– → Br^–                                 ∆H = -55 kcalmol^-1

Since, hydrogen has similarities with alkali metals as well as halogens; it is difficult to find the right position in the periodic table. However, in most of its compounds hydrogen exists in+1 oxidation state. Therefore, it is reasonable to place the hydrogen in group 1 along with alkali metals as shown in the latest periodic table published by IUPAC.

Question 2.
What do you understand by –

1. Electron-deficient
2. Electron-precise
3. Electron-rich compounds of hydrogen? Provide justification with suitable examples.

Answer:

1. Electron deficient hydrides:
   Compounds in which central atom has an incomplete octet, are called electron-deficient hydrides. For example, BeH₂ , BH₃  are electron deficient hydrides
2. Electron precise hydrides:
   Those compounds in which exact number of electrons are present in a central atom or the central atom contains complete octet are called precise hydrides e.g., CH₄ , SiH₄, GeH₄ etc. are precise hydrides.
3. Electron rich hydrides:
   Those compounds in which central atom has one or more lone pair of excess electrons are called electron-rich hydrides. e.g., NH₃, H₂O.

Question 3.
Explain the uses of hydrogen.
Answer:
1. Over 90 % hydrogen produced in the industry is used for synthetic applications. One such process is the Haber process which is used to synthesis ammonia on large scales. Ammonia is used for the manufacture of chemicals such as nitric acid, fertilizers and explosives.
N₂ + 3H₂  2NH
2. It can be used to manufacture the industrial solvent, methanol from carbon monoxide using copper as a catalyst.
CO + 2H₂  CH₃OH
3. Unsaturated fatty oils can be converted into saturated fats called Vanaspati (margarine) by the reduction reaction with \(\frac{P_{t}}{H_{2}}\)
4. In metallurgy, hydrogen can be used to reduce many metal oxides to metals at high temperatures.
CuO + H₂ → Cu + H₂O

WO₃ + 3H₂ → W + 3H₂O
5. Atomic hydrogen and oxy-hydrogen torches are used for cutting and welding.
6. Liquid hydrogen is used as a rocket fuel.
7. Hydrogen is also used in fuel cells for generating electrical energy. The reversible uptake of hydrogen in metals is also attractive for rechargeable metal hydride battery.

Question 4.
What is the permanent hardness of water? How is it removed?
Answer:
The permanent hardness of water is due to the presence of soluble salts of magnesium and calcium in the form of chlorides and sulphates in it. It can be removed by adding washing soda, which reacts with these metal {M = Ca or Mg) chlorides and sulphates in hard water to form insoluble carbonates.

MCl₂ + Na₂CO₃ → MCO₃+ 2NaCl
MSO₄ + Na₂CO₃ → MCO₃ + Na₂SO₄

In another way to soften the hard water is by using a process called ion-exchange. That is, hardness can be removed by passing through an ion-exchange bed like zeolites or a column containing ion-exchange resin. Zeolites are hydrated sodium alumino-silicates with a general formula, NaO . Al₂O₃. ^xSiO₂. ^yH₂O (x = 2 to 10, y = 2 to 6).

Zeolites have porous structure in which the monovalent sodium ions are loosely held and can be exchanged with hardness producing metal ions (M= Ca or Mg) in water. The complex structure can conveniently be represented as Na₂ – Z with sodium as exchangeable cations.
Na₂ – Z + M²⁺ → M – Z + 2Na⁺

When exhausted, the materials can be regenerated by treating with aqueous sodium chloride. The metal ions (Ca² and Mg²⁺) caught in the zeolite (or resin) are released and they get replenished with sodium ions.
M – Z + 2NaCl → Na₂ – Z + MCl₂

Question 5.
Discuss the reaction of hydrogen with (i) Oxygen (ii) Halogens (iii) Alkali metals.
Answer:
(i) Reaction of hydrogen with oxygen.
Hydrogen reacts with oxygen to give water. This is an explosive reaction and releases lot of energy. This is used in fuel cells to generate electricity.
2H₂ + O₂ → 2H₂O

(ii) Reaction of hydrogen with halogens.
Similarly, hydrogen also reacts with halogens to give corresponding halides. Reaction with fluorine takes place even in dark with explosive violence while with chlorine at room temperature under the light. It combines with bromine on heating and reaction with iodine is a photochemical reaction.
2H₂ + O₂ → 2H₂O
In the above reactions, the hydrogen has an oxidation state of +1.

(iii) Reaction of hydrogen with alkali metals:
It also has a tendency to react with reactive metals such as lithium, sodium, and calcium to give corresponding hydrides in which the oxidation state of hydrogen is -1.
2Li + H₂ → 2 LiH
2Na + H₂ → 2NaH

These hydrides are used as reducing agents in synthetic organic chemistry. It is used to prepare other important hydrides such as lithium aluminium hydride and sodium borohydride.
4 LiH + AlCl₃ → Li[AlH₄] + 3LiCl
4 NaH + B(OCH₃)₃ → Na[BH₄] + 3CH₃ONa

Question 6.
Explain the structure of hydrogen peroxide.
Answer:
Both in gas-phase and liquid-phase, the molecule adopts a skew confirmation due to repulsive interaction of the OH bonds with lone-pairs of electrons on each oxygen atom. Indeed, it is the smallest molecule known to show hindered rotation • about a single bond.

H₂O₂ has a non-polar structure. The molecular dimensions in the gas phase and solid phase differ as shown in figure 4.5. Structurally, H₂O₂ is represented by the dihydroxyl formula in which the two OH groups do not lie in the same plane.

One way of explaining the shape of hydrogen peroxide is that the hydrogen atoms would lie on the pages of a partly opened book, and the oxygen atoms along the spine. In the solid phase of molecule, the dihedral angle reduces to 90.2° due to hydrogen bonding and the O-O-H angle expands from 94.8° to 101.9°.

Question 7.
Explain the uses of hydrogen compounds.
Answer:

• The hydrogen compounds such as sodium borohydride (NaBH₄) and lithium aluminium hydride (LiAlH₄) are commonly used as reducing agents in organic chemistry.
• Hydrides such as sodium hydride (NaH) and potassium hydride (KH) are used as strong bases in organic synthesis.
• Calcium hydride is used as a desiccant to remove moisture from organic solvents.
• Hydride complexes are catalysts.
• Atomic hydrogen and oxy-hydrogen torches for cutting and welding.
• Hydrogen is used in fuel cells for generating electrical energy.
• Liquid hydrogen is used as a rocket fuel as well as in space research.
• Metallic hydrides are used in battery applications.

Question 8.
Write notes on intermolecular hydrogen bonding.
Answer:
Intermolecular hydrogen bonds occur between two separate molecules. They can occur between any number of like or unlike molecules as long as hydrogen donors and acceptors are present in positions which enable the hydrogen bonding interactions. For example, intermolecular hydrogen bonds can occur between ammonia molecule themselves or between water molecules themselves, or between ammonia and water.

Water molecules form strong hydrogen bonds with one another. For example, each water molecule is linked to four others through hydrogen bonds. The shorter distances (100 pm) correspond to covalent bonds (solid lines), and the longer distances (180 pm) correspond to hydrogen bonds (dotted lines).

In ice, each atom is surrounded tetrahedrally by four water molecules through hydrogen bonds. That is, the presence of two hydrogen atoms and two lone pairs of electrons on oxygen atoms in each water molecule allows the formation of a three-dimensional structure. This arrangement creates an open structure, which accounts for the lower density of ice compared with water at 0°C. While in liquid water, unlike ice where hydrogen bonding occurs over a long-range, the strong hydrogen bonding prevails only in a short-range and therefore the denser packing.

Question 9.
What is hydrogen bonding? Discuss its properties and applications.
Answer:
Hydrogen bonding is one of the most important natural phenomena occurring in chemical and biological sciences. These interactions play a major role in the structure of proteins and DNA. When a hydrogen atom (H) is covalently bonded to a highly electronegative atom such as fluorine (F) or oxygen (O) or nitrogen (N), the bond is polarized.

Due to this effect, the polarized hydrogen atom is able to form a weak electrostatic interaction with another electronegative atom present in the vicinity. This interaction is called a hydrogen bond (20 – 50 kJ mol^-1) and is denoted by dotted lines (………).

It is weaker than the covalent bond (> 100 kJ mol^-1) but stronger than the vander Waals interaction (< 20 kJ mol^-1). Hydrogen bond has a profound effect on various physical properties including vapour pressure (H₂O and H₂S), boiling point, miscibility of liquids (H₂O and C₂H₅OH), surface tension, densities, viscosity, heat of vaporization and fusion, etc. Hydrogen bonds can occur within a molecule (intramolecular hydrogen bonding) and between two molecules of the same type or different type (intermolecular hydrogen bonding).

A hydrogen bond occurs not only in simple molecules but also in complex biomolecules such as proteins, and they are crucial for biological processes. For example, hydrogen bonds play an important role in the structure of deoxyribonucleic acid (DNA), since they hold together the two helical nucleic acid chains (strands).

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11th Computer Science Guide Arrays and Structures Text Book Questions and Answers

Book Evaluation

Part I

Choose The Correct Answer

Question 1.
which of the following is the collection of variables of the same type that are referenced by a common name ?
a) int
b) float
c) Array
d) class
Answer:
c) Array

Question 2.
Array subscripts is always starts with which number ?
a) -1
b) 0
c) 2
d) 3
Answer:
b) 0

Question 3.
int age[ ]={6,90,20,18,2}; How many elements are there in this array?
a) 2
b) 5
c) 6
d) 4
Answer:
b) 5

Question 4.
cin>>n[3]; To which element does this statement accepts the value?
a) 2
b) 3
c) 4
d) 5
Answer:
c) 4

Question 5.
By default, the string end with which character?
a) \0
b) \t
c) \n
d) \b
Answer:
a) \0

Part – II

Very Short Answers

Question 1.
What is Traversal in an Array?
Answer:
Accessing each element of an array at least once to perform any operation is known as “Traversal”. Displaying all the elements in an array is an example of “traversal”.

Question 2.
What is Strings?
Answer:
A string is defined as a sequence of characters where each character may be a letter,’ number or a symbol.
Every string is terminated by a null (\0) character which must be. appended at the end of the string.

Question 3.
What is the syntax to declare two – dimensional array? ‘
Answer:
The declaration of a 2-D array is
datatype array_name[row – size] [col – size];
In the above declaration, data-type refers to any valid C++ data – type, array _ name refers to the name of the 2 – D array, row – size refers to the number of rows and col-size refers to the number of columns in the 2 – D array.

Part – III

Short Answers

Question 1.
Define an Array. What are the types?
Answer:
An array is a collection of variables of the same type that are referenced by a common name.
There are different types of arrays used in C++. They are:

• One-dimensional arrays
• Two-dimensional arrays
• Multi-dimensional arrays

Question 2.
With note an Array of strings.
Answer:
An array of strings is a two – dimensional character array. The size of the first Index (rows) denotes the number of strings and the size of the second index (columns) denotes the maximum length of each string. Usually, an array of strings are declared in such a way to accommodate the null character at the end of each string. For example, the 2-D array has the declaration:
char name [7][10];
In the above declaration,
No. of rows = 7;
No. of columns = 10;
We can store 7 strings each with a maximum length of 10 characters.

Question 3.
Write a C++ program to accept and print your name?
Answer:
PROGRAM
#include<iostream>
using namespace std;
int main( )
{
char str[100];
cout<< “Enter your name :”;
cin.get(str,100);
cout<< “You name is : ” << str <<endl;
return 0;
}
Output

Part – IV

Explain In Detail

Question 1.
write a c++ program to find the difference between two matrix.
Answer:
PROGRAM
#include<iostream>
#include<conio.h>
using namespace std;
int main( )
{
int row, col, m1[10][10], m2[10][10], sum[10][10];
cout<<“Enter the number of rows : “;
cin>>row;
cout<<“Enter the number of columns :”;
cin>>col;
cout<< “Enter the elements of first matrix: “<<endl;
for (int i = 0;i<row;i++ )
for (int j = 0;j <col;j++ )
cin>>m1[i][j];
cout< < “Enter the elements of second matrix: “<<endl;
for (int i = 0;i<row;i++ )
for (int j = 0;j<col;j++ )
< cin>>m2[i][j];
cout<<“Output: “<<endl;
for (int i = 0;i<row;i++ )
{
for (int j = 0;j<col;j++ )
{
sum[i][j]=m1[i][j] – m2[i][j]); cout<<sum[i][j]<<“”;
}
cout<<endl<<endl;
}
getch( );
return 0;
}
Output

Question 2.
How will you pass two dimensional array to a function explain with example.
Answer:
Passing 2″D array to a function:
C++ program to display values from two dimensional array.
#include<iostream>
using namespace std;
void display (int n[3][2]);
int main( )
{
int num[3][2] = { {3, 4}, {9, 5>, {7, 1} } ;
display(num);
return 0;
}
void display(int n[3][2])
{
cout << “\n Displaying Values” << endl; for (int i=0; i<3; i++)
{
for (int j=0; j<2; j++)
{
cout << n[i][j] << “”;
}
cout << endl << endl;
}
}
Output
Displaying Values
3 4
9 5
7 1
In the above program, the two-dimensional array num is passed to the function display
( ) to produce the results.

11th Computer Science Guide Arrays and Structures Additional Questions and Answers

Choose The Correct Answer (1 Mark)

Question 1.
The size of the array is referred to as its ………………..
(a) dimension
(b) direction
(c) location
(d) space
Answer:
(a) dimension

Question 2.
…………… is an easy way of storing multiple values of the same type referenced by a common name.
a) Variables
b) Literals
c) Array
d) None of these
Answer:
c) Array

Question 3.
Displaying all the elements in an array is an example of ………………..
(a) memory allocation
(b) call by reference
(c) traversal
(d) none of these
Answer:
(c) traversal

Question 4.
A (n) ………………….. is a collection of variables of the same type that are referenced by a common name.
a) Structures
b) Array
c) Unions
d) None of these
Answer:
b) Array

Question 5.
During ……………….. the array of elements cannot be initialized more than its size.
(a) declaration
(b) initialization
(c) assigning
(d) execution
Answer:
(b) initialization

Question 6.
The …………….. of the array is referred to as its dimension.
a) Elements
b) Size
c) Format
d) None of these
Answer:
b) Size

Question 7.
Pass an array to a function in C++, the function needs the array name as ………………..
(a) a function
(b) an argument
(c) global object
(d) string
Answer:
(b) an argument

Question 8.
…………………. is a type of arrays used in C++.
a) One-dimensional array
b) Two-dimensional array
c) Multidimensional array
d) All the above
Answer:
d) All the above

Question 9.
A structure without a name tag is called ………………..
(a) homogenous structure
(b) anonymous structure
(c) array of structure
(d) dynamic memory
Answer:
(b) anonymous structure

Question 10.
A one-dimensional array represents values that are stored in a single …………….
a) Row
b) Column
c) Either A or B
d) None of these
Answer:
c) Either A or B

Question 11.
Array size should be specified with …………………
a) square brackets[ ]
b) Parenthesis ( )
c) Curly braces{ }
d) Angle brackets < >
Answer:
a) square brackets[ ]

Question 12.
In an array declaration, ……………… defines how many elements the array will hold.
a) array_name
b) array_size
c) data_type
d) None of these
Answer:
b) array_size

Question 13.
In an array declaration, …………………. declares the basic type of the array, which is the type of each element in the array.
a) array_name
b) array_size
c) data type
d) None of these
Answer:
c) data type

Question 14.
In an array declaration, ……………….. specifies the name with which the array will be referenced
a) array_name
b) array_size
c) data type
d) None of these
Answer:
a) array_name

Question 15.
The array subscript always starts with ………………
a) 0
b) 1
c) -1
d) None of these
Answer:
a) 0

Question 16.
The subscript always is a(n) ………………value.
a) Integer
b) Unsigned integer
c) Signed integer
d) float
Answer:
b) Unsigned integer

Question 17.
In Turbo C++, int data type requires …………….. bytes of memory.
a) 4
b) 8
c) 2
d) 1
Answer:
c) 2

Question 18.
In Dev C++, int data type requires ………………. bytes of memory,
a) 4
b) 8
c) 2
d) 1
Answer:
a) 4

Question 19.
The memory space allocated for an array can be calculated using the -formula.
a) Number of bytes allocated for the type of array + Number of elements
b) Number of bytes allocated for the type of array x Number of elements
c) Number of bytes allocated for the type of array – Number of elements
d) None of these
Answer:
b) Number of bytes allocated for the type of array x Number of elements

Question 20.
An array can be initialized at the time of its ………………
a) Declaration
b) Process
c) Either A or B
d) None of these
Answer:
a) Declaration

Question 21.
Unless an array is initialized, all the array elements contain ……………..values.
a) Null
b) Default
c) Garbage
d) None of these
Answer:
c) Garbage

Question 22.
While declaring and Initializing values In an array, the values should be given within the ……………..
a) square brackets[ ]
b) Parenthesis ()
c) Curly braces{ }
d) Angle brackets < >
Answer:
c) Curly braces{ }

Question 23.
The …………….. of an array may be optional when the array is initialized during declaration.
a) Data type
b) Size
c) Name
d) None of these
Answer:
b) Size

Question 24.
The subscript in the bracket can be a(n) ……………….
a) Variable
b) Constant
c) Expression that evaluates to an integer
d) Either A or B or C
Answer:
d) Either A or B or C

Question 25.
Accessing each element of an array at least once to perform any operation is known as ………………..
a) Traversal
b) Process
c) Reference
d) None of these
Answer:
a) Traversal

Question 26.
…………………. is a process of finding a particular value present in a given set of numbers.
a) Filtering
b) Searching
c) Seeking
d) None of these
Answer:
b) Searching

Question 27.
The ………………. compares each element of the list with the value that has to be searched until all the elements in the array have been traversed and compared.
a) Linear search
b) Sequential search
c) Either A or B
d) None of these
Answer:
c) Either A or B

Question 28.
A ……………. is defined as a sequence of characters where each character may be a letter, number, or a symbol.
a) String
b) Character
c) Literal
d) Identifier
Answer:
a) String

Question 29.
In C++, there is no basic data type to represent a …………….
a) String
b) Character
c) Literal
d) float
Answer:
a) String

Question 30.
How much memory required for the following array?
char country[6];
a) 12 bytes
b) 6 bytes
c) 60 Bytes
d) 24 bytes
Answer:
b) 6 bytes

Question 31.
…………….. is a way of initializing the character array:
a) char country[6]={T, ‘N’ ‘D’ ‘I’, ‘A’, ‘\0’};
b) char country[ ]=”INDIA”;
c) char country[ ]={T, ‘N’, ‘D’, T, ‘A’ ‘\0’};
d) Either A or B or C
Answer:
d) Either A or B or C

Question 32.
Which is a correct statement from the following?
a) At the end of the string, a null character is automatically added by the compiler.
b) If the size of the array is not explicitly mentioned, the compiler automatically calculates the size of the array based on the number of elements in the list and allocates space accordingly.
c) In the initialization of the string, if all the characters are not initialized, then the rest of the characters will be filled with NULL.
d) All the above
Answer:
d) All the above

Question 33.
In C++,………………. is used to read a line of text including blank spaces.
a) cin.get( )
b) cin
c) put( )
d) None of these
Answer:
a) cin.get( )

Question 34.
………………. function can read the characters till it encounters a newline character or a delimiter specified by the user.
a) getline( )
b) put
c) puts( )
d) None of these
Answer:
a) getline( )

Question 35.
…………………. arrays are a collection of similar elements where the elements are stored in a certain number of rows and columns.
a) One dimensional
b) Two dimensional
c) Multidimensional
d) All the above
Answer:
b) Two dimensional

Question 36.
In two dimensional arrays, …………………. size is compulsory.
a) Column
b) Row
c) Both A and B
d) None of these
Answer:
a) Column

Question 37.
In two dimensional arrays, …………….. size is optional.
a) Column
b) Row
c) Both A and B
d) None of these
Answer:
b) Row

Question 38.
int A[3][4 j; How many elements are there in the array “A”?
a) 3
b) 4
c) 7
d) 12
Answer:
d) 12

Question 39.
The two-dimensional array uses ………………. index values to access a particular element in it.
a) two
b) one
c) three
d) many
Answer:
a) two

Question 40.
In a two dimensional array, the first index specifies the …………….. value.
a) Column
b) Row
c) Both A and B
d) None of these
Answer:
b) Row

Question 41.
In a two dimensional array, the second index specifies the …………… value.
a) Column
b) Row
c) Both A and B
d) None of these
Answer:
a) Column

Question 42.
The two-dimensional array can be viewed as a …………………
a) List
b) Matrix
c) Linear block
d) None of these
Answer:
b) Matrix

Question 43.
There are …………… types of 2-D array memory representations.
a) two
b) one
c) three
d) many
Answer:
a) two

Question 44.
……………… is a type of 2-D array memory representation.
a) Row-Major order
b) Column-Major order
c) Either A or B
d) None of these
Answer:
c) Either A or B

Question 45.
In row-major order, all the elements are stored ……………… in contiguous memory locations.
a) Column by Column
b) Row by Row
c) Both A and B
d) None of these
Answer:
b) Row by Row

Question 46.
In column-major order, all the elements are stored ………………. in contiguous memory locations.
a) Column by Column
b) Row by Row
c) Both A and B
d) None of these
Answer:
a) Column by Column

Question 47.
An array of strings is a ………………. dimensional character array,
a) Two
b) One
c) Multi
d) None of these
Answer:
a) Two

Question 48.
In a two-dimensional character array, the size of the first index (rows) denotes the ……………….
a) Maximum length of each string
b) Number of strings
c) Maximum characters
d) None of these
Answer:
b) Number of strings

Question 49.
In a two-dimensional character array, the size of the second index (rows) denotes the ……………….
a) Maximum length of each string
b) Number of strings
c) Maximum characters
d) None of these
Answer:
a) Maximum length of each string

Question 50.
char Name[6][10]; How many strings can be stored in the above array?
a) 10
b) 60
c) 6
d) 16
Answer:
c) 6

Question 51.
To pass an array to a function in C++, the function needs the ………….. as an argument,
a) Array name
b) Array type
c) Dimension
d) None of these
Answer:
a) Array name

Very Short Answers (2 Marks)

Question 1.
What is the formula to calculate the memory space allocated for an array?
Answer:
A number of bytes allocated for the type of array x Number of elements.

Question 2.
What are the types of arrays?
Answer:
There are different types of arrays used in C++. They are:

1. One-dimensional arrays
2. Two-dimensional arrays
3. Multi-dimensional arrays

Question 3.
Write about returning structures from functions.
Answer:
A structure can be passed to a function through its object. Therefore, passing a structure to a function or passing a structure object to a function is the same because the structure object represents the structure. Like a normal variable, a structure variable(structure object) can be passed by value or by references/addresses. Similar to built-in data types, structures also can be returned from a function.

Question 4.
Write the syntax and example for one-dimensional declaration and initialization.
Answer:
Syntax:
[size] = {value-1,value-2,………….,value-n};
Example:

Question 5.
What is a global object?
Answer:
Objects declared along with structure definition are called global objects.

Question 6.
Write a note on strings.
Answer:
strings:
A string is defined as a sequence of characters where each character may be a letter, number or symbol. Each element occupies one byte of memory. Every string is terminated by a null C\0′ ASCII code 0) character which must be appended at the end of the string.

Question 7.
Differentiate array and structure.
Answer:
Array:

• An array is a collection of variables of the same data type.
• Array data are accessed using index.
• Array allocates static memory
• Array element access takes lesser time.

Structure:

• A structure is a collection of variables of different data type.
• Structure elements are accessed using operator.
• Structures allocate dynamic memory.
• Structure elements take more time.

Short Answers (3 Marks)

Question 1.
Write about the initialization of 2 – D array.
Answer:
The array can be initialized in more than one way at the time of 2-D array declaration.
For example
int matrix[4][3] = {
{10,20,30},// Initializes row 0
{40,50,60},// Initializes row 1
{70,80,90},// Initializes row 2
{100,110,120}// Initializes row 3
};
int matrix[4][3] = {10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120};
Array’s row size is optional but column size is compulsory.

Question 2.
What is subscript? Give its rules,
Answer:
subscript:
Each element has a unique index number starting from 0 which is known as a subscript.
Rules for subscript:

• The subscript always starts with 0.
• It should be an unsigned integer value.
• Each element of an array is referred to by its name with a subscript index within the square bracket.

For example:
num[3] refers to the 4th element in the array.

Question 3.
How memory locations are allocated to a one-dimensional array?
Answer:
Memory representation of a one-dimensional array:
The amount of storage required to hold an array is directly related to type and size.
The following figure shows the memory allocation of an array with five elements.

The above figure clearly shows that the array num is an integer array with 5 elements. Here, there is a total of 5 elements in the array, where for each element, 4 bytes in Dev C++ (or)2 bytes in Turbo C++ will be allocated. Totally 20 bytes will be allocated for this array (In Turbo C++ 10 Bytes).

Question 4.
Tabulate the memory requirement of data type in Turbo C++ and Dev C++.
Answer:

Data type	Turbo C++	Dev C++
char	1	1
int	2	4
float	4	4
long	4	4
double	8	8
long double	10	10

Question 5.
Explain character Array (String) creation with syntax and example.
Answer:
To create any kind of array, the size (length) of the array must be known in advance, so that the memory locations can be allocated according to the size of the array. Once an array is created, its length is fixed and cannot be changed during run time, This is shown in the following figure.

Syntax of array declaration is:
char array_name[size];
In the above declaration, the size of the array must be an unsigned integer value.

For example,
char country[6];
Here, the array reserves 6 bytes of memory, for storing’ a seqi characters. The length of the string cannot be more than 5 characters and one location is reserved for the null character at the end.

Question 6.
What is an array of strings?
Answer:
An array of strings is a two – dimensional character array. The size of the first index (rows) denotes the number of strings and the size of the second index (columns) denotes the maximum length of each string. Usually, an array of strings are declared in such a way to accommodate the null character at the end of each string. For example, the 2 – D array has the declaration: char Name[6][10];
In the above declaration, the 2 – D array has two indices which refer to the row size and column size, that is 6 refers to the number of rows, and 10 refers to the number of columns.

Question 7.
Write note on getline( ) function.
Answer:
In C++, getline( ) is also used to read a line . of text from the input stream. It can read the characters tilt it encounters a newline character or a delimiter specifier’ by the user. This function is available in the header.

Question 8.
How memory represented for a 2-D array?
Answer:
There are two types of 2-D array memory representations. They are:

• Row Major order
• Column Major order

For example:
int A[4][3]={ { 8,6,5}, { 2,1,9}, {3,6,4}, {4,3,2} };
Row Major order:
In row-major order, all the elements are stored row by row in continuous memory locations, that is, ail the elements in first row, then in the second row and soon. The memory representation of row-major order is as shown below.

Question 9.
How 2-D character array initialized and stored in memory? Explain.
Answer:
2D char array initialization:

For example:
char Name[6][10] = {“Mr. Bean’; “Mr.Bush”
“Nicole”, “Kidman” “Arnold”, “Jodie”};
In the above’ example, the 2-D array is initialized with 6 strings, where the string is a maximum of 9 characters long since the last character is null. The memory arrangement of a 2-D array is shown below and ail the strings are stored in continuous locations.

Question 10.
What is called nested structure? Give example.
Answer:
The structure declared within another structure is called a nested structure. Nested structures act as members of another structure and the members of the child structure can be accessed as parent structure name. Child structure name. Member name, struct dob
{
int date;
char month[3];
int year;
} ;
Values can be assigned to this structure as follows.
dob = {25, “DEC”, 2017}

Question 11.
Write a program to pass an array as an argument to a function.
Answer:
In C++, arrays can be passed to a function as an argument.
To pass an array to a function in C++, the function needs the array name as an argument.
C++ program-to display marks of 5 students (one-dimensional array)
#indude<iostream>
using namespace std;
void display (int m[5]);
int main( )
{
int marks[5]={88, 76, 90, 61, 69};
display(marks);
return 0;
}
void’ display (int m[5])
{
cout << “\n. Display Marks: ” << end!; for (int i=0; i<5; i++)
{
cout <-< “Student” << i+1 << ” << m[i]<<endl;
}
}
Output
Display Marks:
Student 1: 88
Student 2: 76
Student 3: 90
Student 4: 61
Student 5: 69

Question 12.
Write a C++ program to pass a 2-D array to a function.
Answer:
C++ program to display values from two dimensional array:
#include<iostream>
using namespace std;
void display (int n[3][2]);
int main( )
{
int num[3][2] = { {3, 4}, (9, 5}, {7,1} };
display(num);
return 0; ‘
}
void display(int n[3][2])
{
cout << “\n Displaying Values” << endl;
for (int i=0; i<3; i++)
{
for (int j=0; j<2; j++)
{
cout << n[i][j] << ”
}
cout << endl << endl;
}
}
Output
Displaying Values
3 4
9 5
7 1

Question 13.
Write a user-defined function to return the structure after accepting value through the keyboard. The structure definition is as follows: struct Item{int item no; float price;};
Answer:
item accept (item i)
{

cout << “\n Enter the Item No:”; cin >> i.no;
cout << “\n Enter the Item Price:”; cin >> i.price;
return i;

}

Explain in Detail (5 Marks)

Question 1.
How will you search an element in a one-dimensional array? Explain linear search.
Answer:
Searching in a one-dimensional array:
Searching is a process of finding a particular value present in a given set of numbers. The linear search or sequential search compares each element of the list with the value that has to be searched until all the elements in the array have been traversed and compared.

Program for Linear Search
#include<iostream>
using namespace std;
int Search(int arr[ ], int size, int value)
{
for (int i=0; <size; i++)
{
if (arr[i] == value)
return i; // return index value
}
return -1;
}
int main( )
{
int num[10], val, id;
for (int i=0; i< 10; i++) .
{
cout<<“\n Enter value” << i+1 <<“=”;
cin>>num[i];
}
cout<< “\n Enter a value to be searched: “;
cin>>val;
id=Search(num,10,val);
if(id==-1) .
cout<< “\n Given value is not found in the array..”;
else
cout<< “\n The value is found at the position” << id+1;
return 0;
}
The above program reads an array and prompts for the values to be searched. It calls the Search() function which receives array, size and value to be searched as parameters. If the value is found, then it returns the array index to the called statement; otherwise, it returns -1.

Question 2.
Explain two-dimensional array with syntax and example.
Answer:
Two-dimensional array:
Two-dimensional (2D) arrays are collections of similar elements where the elements are stored in a certain number of rows and columns. An example m x n matrix where m denotes the number of rows and n denotes the number of columns is shown in the following figure, int arr[3][3];
2D array conceptual memory representation

The array arr can be conceptually viewed in matrix form with 3 rows and columns. point to be noted here is since the subscript starts with 0 arr [0][0] represents the first element.

The syntax for declaration of a 2-D array is:
data-type array_name[row-size][col-size];
In the above declaration, data-type refers to any valid C++ data-type, array_name refers to the name of the 2-D array, row-size refers to the number of rows and col-size refers to the number of columns in the 2-D array.

For example:
int A[3][4];
In the above example, A is a 2-D array, 3 denotes the number of rows and 4 denotes the number of columns. This array can hold a maximum of 12 elements.

Case Study

Question (1)
Write a program to accept the marks of 10 students and find the average, maximum and minimum marks.
Answer:
PROGRAM
#include<iostream>
using namespace std;
int main( )
{
int marks[10], sum=0,max,min;
float avg;
cout<< “\n Enter Mark 1” << “=”;
cin>> marks[0];
max=marks[0];
min=marks[0];
for(int i=1; i< 10; i++)
{
cout<< “\n Enter Mark” << i+1 << “=”;
cin>> marks[i];
sum=sum+marks[i];
if (marks[i]>max)
max = marks[i];
if (marks[i]<min)
min = marks[i];
}
avg=sum/10.0;
cout<< “\n The Total Marks: ” << sum;
cout<< “\n The Average Mark: ” <<avg;
cout<< “\n The Maximum Mark: ” <<max;
cout<< “\n The Minimum Mark: ” <<min;
}
Output

Question (2)
Write a program to accept rainfall recorded in four metropolitan cities of India and find the city that has the highest and lowest rainfall.
Answer:
PROGRAM
#include<iostream>
#include<string.h>
using namespace std;
int main( )
{
int rate[10],min,n;
char shop[5][20];
char minshop[20];
cout<<“\nHow many Shops
cin>>n;
for(int i=0;i<n;i++)
{
cout<<“\nEnter Name of the Shop “<<i+1<<” :”;
cin> >shop[i];
cout<<“\nEnter price of Product-X at “<<shop[i]<<” :”;
cin>>rate[i];
}
min=rate[0];
strcpy(minshop,shop[0]);
for(int i=l;i<n;i++)
{
if (rate[i]<min)
{
min = rate[i];
strcpy(minshop,shop[i]);
}
}
cout< < “\n The Lowest cost of the Proudct=X at the” “<<minshop <<“is”<<min;
}
Output

Question (3)
Survey your neighboring shops and find the price of any particular product of interest and suggest where to buy the product at the lowest cost.
Answer:
PROGRAM
#include<iostream>
#include<string.h>
using namespace std;
int main( )
{
int rate[10],min,n;
char shop[5][20];
char minshop[20];
cout<<“\nHow many Shops “;
cin>>n;
for(int i=0;i<n;i++)
{
cout<<“\nEnter Name of the Shop “<<i+l<<” :”;
cin>>shop[i];
cout<<“\nEnter price of Product-X at “<<shop[i]<<“:”;
cin> >rate[i];
}
min=rate[0];
strcpy(nninshop,shop[0]);
for(int i=l;i<n;i++)
{
if (rate[i]<min)
{
min = rate[i];
strcpy(minshop,shop[i]);
}
}
cout< < “\n The Lowest cost of the Proudct=X at the ” <<minshop <<“is”<<min;
}
Output

STRUCTURES

Book Evaluation

Part -I

Choose The Correct Answer

Question 1.
The data elements in the structure are also known as ……………..
a) objects
b) members
c) data
d) records
Answer:
b) members

Question 2.
Structure definition is terminated by ……………..
a) :
b) }
c) ;
d) ::
Answer:
c) ;

Question 3.
What will happen when the structure is declared?
a) it will not allocate any memory
b) it will allocate the memory
c) it will be declared and initialized
d) it will be only declared
Answer:
b) it will allocate the memory

Question 4.
What is the out of this program?
#include<iostream>
#include<string.h>
using namespace std;
int main( )
{
struct student
{
int n;
char name[10];
};
students;
s.n = 123;
183
strcpy(s.name, “Balu”);
cout<<s.n;
co
ut<< s.name <<endl;
return 0;
}
a) 123Balu
b) BaluBalu
c) Balul23
d) 123 Balu
Answer:
a) 123Balu

Question 5.
A structure declaration is given below.
struct Time
{
int hours;
int minutes;
int seconds;
}t;
Using the above declaration which of the following refers to seconds.
a) Time.seconds
b) Time::seconds
c) seconds
d) t. seconds
Answer:
d) t. seconds

Question 6.
What will be the output of this program?
#include <iostream>
using namespace std;
struct ShoeType
{
string name; double price;
>; , ‘ ‘
int main()
184 {
ShoeType shoe1, shoe2;
shoe1.name = “Adidas”;
shoe1.price = 9.99;
cout<< shoe1.name<< ” #. “<< shoe1.
price<<endl;
shoe2 = shoe1;
shoe2.price = shoe2.price / 9;
cout<< shoe2.name<< ” # “<< shoe2.price;
return 0;

a) Adidas # 9.99 Adidas #1.11	b) Adidas # 9.99 Adidas # 9.11
c) Adidas # 9.99 Adidas # 11.11	d) Adidas #9.11 Adidas # 11.11

Answer:
a) Adidas # 9.99 Adidas #1.11

Question 7.
Which of the following is a properly defined structure?
a) struct {int num;}
b) struct sum {int num;}
c) struct sum int sum;
d) struct sum {int num;};
Answer:
d) struct sum {int num;};

Question 8.
A structure declaration is given below.
struct employee
{
int empno;
char ename[10];
} e[5];
Using the above declaration which of the following statement is correct.
a) cout<<e[0].empno<<e[0].ename;
b) cout<<e[0].empno<<ename;
c) cout< <e[0]->empno< <e[0]->ename;
d) cout<<e.empno<<e.ename;
Answer:
a) cout<<e[0].empno<<e[0].ename;

Question 9.
Which of the following cannot be a structure member?
a) Another structure
b) Function
c) Array
d) variable of double datatype
Answer:
b) Function

Question 10.
When accessing a structure member, the identifier to the left of the dot operator is the name of
a) structure variable
b) structure tag
c) structure member
d) structure-function
Answer:
a) structure variable

Part – II

Very Short Answers

Question 1.
Define structure. What is its use?
Answer:
Definition:
The structure is user-defined which has the combination of data items with different data types. This allows to a group of variables of mixed data types together into a single unit.
Use: The structure provides a facility to store different data types as a part of the same logical element in one memory chunk adjacent to each other.

Question 2.
To store 100 integer numbers which of the following is good to use?
Answer:
Array or Structure State the reason.
In any situation when more than one variable is required to represent objects of uniform data types, an array can be used. If the elements are of different data types, then the array cannot support them.
The structure provides a facility to store different data types as a part of the same logical element in one memory chunk adjacent to each other. So, to store 100 integer numbers Array is good.

Question 3.
What is the error in the following structure definition.
Answer:
struct employee {inteno; charename[20]; char dept;}
Employee e1,e2;

Error:
In the above code objects for employee strcture is created at the end of structure definition. So,structure name is not needed. It may written as:
struct employee
{
int eno;
char ename[20];
char dept;
}e1,e2;

Question 4.
Write a structure definition for the structure student containing exam no, name and an array for storing five subject marks.
Answer:
Structure definition:
struct student
{
int examno;
char sname[30];
int mark [5];
};

Question 5.
Why for passing a structure to a function call by reference is advisable to us?
Answer:
In call by reference, any change made to the contents of structure variable inside the function are reflected back to the calling function. Otherwise changes in the structure content within the function will not implement in the structure content.

Question 6.
What is the size of the following highlighted variable in terms of byte if it is compiled in dev C++
Answer:
struct A{ float f[3]; char ch[5];long double d;>;
struct B{ A a; int arr[2][3];}b[3]
struct A {float f[3]; char ch[5]; long double d;>;
Memory requirements (Using Dev C++):

Variable	Memory requirement
float f(3);	12 Bytes
char ch[5];   ,	5 Bytes
double d;	8 Bytes

Using Turbo C++ also the same memory is needed. (Only int data type requirement is differ. Here no int members. So, no change in the requirement.)
struct B { A a; int arr[2][3];}b[3];
Memory requirements (Using Dev C++):

Variable	Memory requirement
A a; (Which is a structure variable)	25 Bytes
int arr[2][3];	24 Bytes
b[3] which is a structure variable of structure B	49 Bytes for each element of b. So, Total requirement of b[3] is 147 Bytes.

Memory requirements (Using Turbo C++):

Variable	Memory requirement
A a; (Which is a structure variable)	25 Bytes
int arr[2][3];	12 Bytes
b[3] which is a structure variable of structure B	37 Bytes for each element of b. So, Total requirement of b[3] is 111 Bytes.

Question 7.
Is the following snippet is fully correct. If not identify the error.
Answer:
struct sum1{ int n1,n2;}s1;
struct sum2{int n1,n2}s2;
cin>>s1.n1>>s1.n2;
s2=s1;
No. It is not fully correct. The following errors are there.
Errors:

Statement	Error
struct sum1 {int n1,n2;}sl;	No Error
struct sum2 {int n1,n2}s2;	Semicolon missing at the end of declaration statement;
cin>>s1.n1>>s1. n2;	No Error
s2-s1;	Objects of different structures can not be directly copied.

Question 8.
Differentiate array and structure.
Answer:
In any situation when more than one variable is required to represent objects of uniform data¬types, array can be used. If the elements are of different data types, then array cannot support. If more than one variable is used, they can be stored in memory but not in adjacent locations. It increases the time consumption while searching.

The structure provides a facility to store different data types as a part of the same logical element in one memory chunk adjacent to each other.

Question 9.
What are the different ways to initialize the structure members?
Answer:
Values can be assigned to structure elements similar to assigning values to variables.
Example:
Consider the following structure: struct Student
{
long int rollno;
int age;
float weight;
}
balu ;
We can initialize as given below:
balu.rollno= 702016;
balu. age=18; ‘
balu.weight= 48.5;
Also, values can be assigned directly as similar to assigning values to Arrays.
balu={702016, 18, 48.5};

Question 10.
What is wrong with the following C++ declarations?
Answer:
A. struct point ( double x, y)
B. struct point { double x, double y >;
C. struct point { double x; double y >
D. struct point { double x; double y; };
E. struct point { double x; double y; >

Errors:
A. struct point (double x, y)
Structure definition must be terminated with;. It is missing. Members must be enclosed in { }. So it may be written as
struct point { double x, y };

B. struct point {double x, double y>;
Structure member declaration must be terminated with; It is missing. So, it may corrected as
struct point {double x; double y;>; or struct point {double x, y;>;

C. struct point {double x; double y>
Structure member declaration and definition must be terminated with ; It is missing. So, it may corrected as
struct point {double x; double y;>; or
struct point { double x, y; >;

D. struct point {double x; double y;};,
No error .
E. struct point {double x; double y;>
– Structure definition must be terminated with ; it is missing. So, it may be corrected as
struct point {double x; double y;>;

Part – III

Short Answers

Question 1.
How will you pass a structure to a function ?
Answer:
A structure variable can be passed to a function in a similar way of passing any argument that is of built-in data type,

1. If the structure itself is an argument, then it is called “call by value”.
2. If the reference of the structure is passed as an argument then it is called, “call by reference”.

Call by value
When a structure is passed as argument to a function using call by value method,any change made to the contents of the structure variable inside the function to which it is passed do not affect the structure variable used as an argument.

Call by reference
In this method of passing the structures to functions, the address of a structure variable / object is passed to the function using address of(&) operator. So any change made to the contents of structure variable inside the function are reflected back to the calling function.

Question 2.
The following code sums up the total of all students name starting with ‘S’ and display it. Fill in the blanks with required statements.
Answer:
struct student {int exam no, lang, eng, phy, che, mat, esc, total; char name[15];>;
int main( )
{
student s[20];
for(int i=0;i<20;i++)
{
…………………. //accept student details
}
for(int i=0;i<20;i++)
{
……………. //check for name starts with’ letter “S”
…………….. // display the detail of the checked name
}
return 0;
}
MODIFIED PROGRAM
using namespace std;
#include<iostream>
struct student
{
int exam_.no,lang,eng,phy,che,mat,esc,total; char name[15];
};
int main( )
{
student s[20];
for(int i=0;i<20;i++)
{
//accept student details
cout<<“\nEnter student name”;
cin>>s[i].name;
cout<<“\nEnter student exam number”;
cin>>s[i].exam_no;
cout<<“\nEnter Languge Mark”;
cin>>s[i].lang;
cout<<“\nEnter Engjish Mark”;
cin>>s[i].eng;
cout<<“\nEnter Physics Mark”;
cin>>s[i].phy;
cout<<“\nEnter Chemistry Mark”;
cin>>s[i].che;
cout<<“\nEnter Maths Mark”;
cin>>s[i].mat;
cout<<“\nEnter Computer Science Mark”;
cin>>s[i].csc;
s[i].total = s[i].lang + s[i].eng + s[i]. phy+s[i].che+s[i].mat+s[i]. csc;
}
cout<<“\nDetails of student name starts with letter S “<<endl;
for(int i=0;i<20;i++)
{
//check for name starts with letter “S” if(s[i].name[0] == ‘S’)
{
// display the detail of the checked name

cout<<“\nName : “<<s[i].
name<<“Total Mark”<<s[i].
total <<endl;
}
}
return 0;
}
Output

Question 3.
What is called nested structure. Give example
Answer:
The structure declared- within another structure is called a nested structure.
Example:
struct Student
{
int age;
float height, weight;
struct dob
{
int date;
char month[4];
int year;
};
}mahesh;
The nested structures act as members of another structure and the members of the child structure can be accessed as parent structure name. Child structure name. Member name.
Example:
mahesh. dob. date
Here

• mahesh is a parent structure name.
• dob is a child structure name
• date is a member of child structure

Question 4.
Rewrite the following program after removing the syntactical error(s), if any.
Answer:
Underline each correction.
struct movie
{
charm_name[10];
charm-Lang[10];
float ticket cost =50;};
Movie;
void main( )
{
gets(m_name);
cin>>m-lang;
return 0; ,
}
MODIFIED PROGRAM
PROGRAM (USING DEV C++)
#include<iostream>
#include<conio.h>
#include<stdio.h>
struct movie
{
char m_name[10];
char m_lang[10];
float ticket_cost;
} Movie;
int main( )
{
std::cout<<“\nEnter Move! Name ;
gets(Movie.m_name);
std::cout<<:”\nEnter Movie Language ,:
std: :cin>>Movie.m -lang;
std::cout<<“\nEnter Ticket Cost: “;
std::cin>>Movie.ticket_cost;
std::cout<<“\nMovie name is : “<
std::cout< <“\nMovie Language is : “<<Movie.m-lang;
std::cout<<“\nTicket cost is : “<<Movie.ticket_cost;
}
Output

Question 5.
What ¡s the difference among the following two programs?
a) #include<iostream.h>
struct point
{
double x;
double y;
};
int main()
{
struct point test;
testx = .25; test.y = .75;
cout< <test.x< ctest.y;
return 0;
}
b) #include
struct .
{
double x;
double y;
} Point;
int main(void)
{
Point test={.25,.75>;
return 0;
}
Answer:
The method of structure initialisation is different.

Question 6.
How to access members of a structure? Give f example.
Answer:
Once the two objects of student structure type are declared, their members can be accessed directly. The syntax for that is using a dot (.) between the object name and the member name.
Syntax is :
Object name. Member

For example:
struct Student
{
longrollno;
int age;
float weight;
}balu, frank;
The elements of the structure Student can be accessed as follows: balu.rollno balu.age balu. weight frank, rollno frank.age frank.weight
balu.rollno
balu.age
balu.weight
frank.rollno
frank.age
frank.weight

Question 7.
Write the syntax and an example for structure.
Answer:
Structure is declared using the keyword ‘struct’. The syntax of creating a structure is given below.
struct structure_name
{
type member_name1;
type member_name2;
} reference_name;
An optional field reference_name can be used to declare objects of the structure type directly.

Example:
struct Student
{
longrollno;
int age;
float weight;
}balu, frank;

Question 8.
For the following structure, definition writes the user-defined function to accept data through the keyboard.
struct date
{
int dd,mm,yy
};
struct item
{
int item id;
char name[10];
float price;
date date_manif;
}
Answer:
USER DEFINED FUNCTION
item accept( )
{
item obj;
cout<<“\n Enter Item Id “;
cin> > obj. item id;
cout<<“\nEnter Name “;
cin>obj.name;
cout<<“\nEnter Price “;
cin>>obj.price;
cout<<“\nEnter Date: date, month and year
cin>>obj.date_manif.dd >> obj.date_manif. mm >> obj.date_manif.yy;
return(obj);
}

Question 9.
What is called an anonymous structure? Give an example.
Answer:
A structure without a name/tag is called anonymous structure, struct
{
long rollno;
int age;
float weight;
} student;
The student can be referred to as a reference name to the above structure and the elements can be accessed like
student, roll no
student.age and
student.weight.

Question 10.
Write a user-defined function to return the structure after accepting value through the keyboard. The structure definition is as follows:
struct Item{int item no;float price;};
Answer:
USER DEFINED FUNCTION
Item accept( )
{
Item obj; ,
cout<<‘AnEnter Item Number and Price “; cin>>obj.item_no>>obj, price.
return(obj);
}

Part-IV

Explain in Detail

Question 1.
Explain the array of structures with examples.
Answer:
A class may contain many students. So, the definition of structure for one student can also be extended to all the students. If the class has 20 students, then 20 individual structures are required. For this purpose, an array of structures can be used.
An array of structures is declared in the same way as declaring an array with built-in data types like int or char.
The following program reads the details of 20 students and prints the same.
#include<iostream>
using namespace std;
struct Student
{
int age;
float height, weight;
char name[30];
};
void main()
{
Student std[20];
int i;
cout<< ” Enter the details for 20 students”<<endl;
for(i=0;i<20;i++)
{
cout<< ” Enter the details of student”<<i+1<<endl;
cout<< ” Enter the age:”<<endl; cin>>std[i].age;
cout<< “Enter the height:”<<endl; cin>>std[i].height;
cout<< “Enter the weight:”<<endl; cin>>std[i].weight;
}
cout<< “The values entered for Age, height and weight are”<<endl;
for(i=0;i<20;i++)
cout<< “Student “<<i+l<< “\t”< <std[i]. age<< “\t”<<std[i].height<< “\t”<<std[i]. weight;
}
Output
Enter the details of 20 students
Enter the details for student1
Enter the age:
18
Enter the height:
160.5
Enter the weight:
46.5
Enter the details for student2
Enter the age:
18
Enter the height:
164.5
Enter the weight:
61.5
………………………………….
…………………………
The values entered for Age, height and weight are
Student 1 18 160.5 46.5
Student 2 18 164.5 61.5
………………………

Question 2.
Explain call by value with respect to structure.
Answer:
A structure variable can be passed to a function in a similar way of passing any argument that is of built-in data type. If the structure itself is an argument, then it is called “call by value”.

Call by value
When a structure is passed as argument to a function using call by value method,any change made to the contents of the structure variable inside the function to which it is passed do not affect the structure variable used as an argument.
Example:
#include<iostream>
using namespace std;
struct Employee
{
char name[50]; ,
int age;
float salary;
};
void printData(Employee); // Function declaration
int main( )
{
Employee p;
cout<< “Enter Full name: “;
cin>>p.name;
cout<< “Enter age: “;
cin>>p.age;
cout<< “Enter salary: “;
cin>>p.salary;
// Function call with structure variable as an argument
printData(p);
return 0;
}
void printData(Employee q)
{
cout<< “\nDisplaying Information.” <<endl;
cout<< “Name: ” << q.name <<endl;
cout<<“Age: ” <<q.age<<endl;
cout<< “Salary:” <<q.salary;
}
Output
Enter Full name: Kumar
Enter age: 55
Enter salary: 34233.4
Displaying Information.
Name: Kumar
Age: 55
Salary: 34233.4
In the above example, a structure named Employee is declared and used. The values that are entered into the structure are name, age and salary of a Employee are displayed using a function named printData( ).

Question 3.
How call by reference is used to pass structure to a function .Give an Example
Answer:
Call by reference
In this method of passing the structures to functions ,the address of a structure variable / object is passed to the function using address of(&) operator. So any change made to the contents of structure variable inside the function are reflected back to the calling function
Example:
#include<iostream>
using namespace std;
struct Employee
{
char name[50];
int age;
float salary;
};
void readData(Employee &);
void printData(Employee);
int main()
{
Employee p;
readData(p);
printData(p);
return 0;
}
void readData(Employee &p)
{
cout<< “Enter Full name: “;
cin.get(p.name, 50);
cout<< “Enter age:
cin>>p.age; ,
cout<< “Enter salary:
cin>>p. salary;
}
void printData(Employee p)
{
cout<< “\nDisplaying Information.” <<endl;
cout<< “Name: ” << p.name <<endl;
cout<<“Age:” <<p.age<<endl;
cout<< “Salary:” <<p.salary;
}
Output
Enter Full name: Kumar
Enter age: 55
Enter salary: 34233.4
Displaying Information.
Name: Kumar
Age: 55
Salary: 34233.4
Structures are usually passed by reference method because it saves the memory space and executes faster.

Question 4.
Write a C++ program to add two distances using the following structure definition
Answer:
struct Distance
{
int feet;
float inch;
}d1, d2, sum;
PROGRAM
#include<iostream>
using namespace std;
struct Distance
{
int feet;
float inch;
} d1, d2, sum;
int main( )
{
cout<<“\nEnter distance 1: feet and inch : “;
cin>>d1.feet>>d1.inch;
cout<<“\nEnter distance 2: feet and inch :
cin>>d2.feet>>d2.inch;
sum.feet = d1.feet + d2.feet;
sum.inch =(d1.inch + d2.inch) – (int) (d1.inch + d2,inch) / 12 * 12;
sum.feet = sum.feet + (d1.inch + d2.inch)/12;
cout<<“\nDitance 1: Feet = “<<d1.feet<<”
Inch = “<<d1.inch;
cout<<“\nDitance 2: Feet = “<<d2.feet<<”
Inch = “<<d2.inch;
cout<<“\nSum of Distance 1 and 2 : Feet = “<<sum.feet<<” Inch = “<<sum.inch;
}
Output

Question 5.
Write a C++ Program to Add two Complex Numbers by Passing Structure to a Function for the following structure definition
Answer:
struct complex
{
float real;
float imag;
};
The prototype of the function is complex add Complex Numbers(complex, complex);
PROGRAM
#include<iostream>
using namespace std;
struct complex
{
float real;
float imag;
};
complex add Complex Numbers (complex obj1,complex obj2)
{
complex obj3;
obj3.real = obj1.reai+obj2,real;
obj3.imag = obj1.imag + obj2.imag;
return(obj3);
}
int main( )
{
complex c1,c2,c3;
cout<<“\nEnter First complex number real and imaginary :”;
cin>>c1,real>>c1.imag;
cout<<“\nEnter Second complex number real and imaginary :”;
cin>>c2.real>>c2.imag;
c3 = addComplexNumbers(c1,c2);
cout<<“\nFirst Complex Number is : “< }
Output

Question 6.
WrIte a C++ Program to declare a structure book containing name and author as character array of 20 elements each and price as Integer. Declare an array of book. Accept the name, author, price detail for each book. Define a user defined function to display the book details and calculate the total price. Return total price to the calling function.
Answer:
PROGRAM
using namespace std;
#include<iostream>
#include<iomanip>
#include<istdio.h>
struct book
{
char bname[20],author[20];
int price;
};
int display(book x[5])
{
int total;
for(int i=0;i<5;i++)
{
total = total + x[i].price;
cout<<“\nBook name : “<<x[i].
bname;
cout<<“\nAuthor name : “<<x[i].
author;
cout<<“\nPrice of the book: “<<x[i].
price;
}
return(total);C++C
}
int main( )
{
book. b[5];
for(int i=0;i<5;i++)
{
cout<<“\nEnter Book name “;
cin>>b[i].bname;
cout<<“\nEnter Author name “;
cin>>b[i].author;
cout<<“\nEnter Book Price “;
cin > > b[i]. price;
}
cout<<“\nDetails of Books”<<endl;
cout<<“\nTotal cost of the book is : Rs.”<<display(b);
}
Output

Question 7.
Write a C++ program to declare and accept an array of professors. Display the details of the department=”COMP.SCI” and the name of the professors start with ‘A’. The structure “college” should contain the following members.
prof-id as integer ,
name and Department as character array
Answer:
PROGRAM
using namespace std;
#include<iostream>
#include<iomanip>
#include<string.h>
struct college .
{
char pname[20],department[20]; int prof-id;
};
void display(college x[5])
{
for(int i=0;i<5;i++)
{
if((strcmp(x[i]. department,”COMP. SCI”)==0) && x[i].pname[0]==’A’)
cout<<x[i].pname«endl;
}
return;
}
int main( )
{
college c[5];
for(int i=0;i <5;i++)
{
cout<<“\nEnter Professor Name “;
cin>>c[i].pname; ,
cout<<“\nEnter Department Name “;
cin> >c[i] .department;
cout< <“\nEnter Professor Id
cin>>c[i].prof-id;
}
cout<<“\nDetails of Comp. Sci. . Dept, Professors whose name starts. with A “<<endl; . display(c);
}
Output

Question 8.
Write the output of the following C++ program
Answer:
#incluçle<iostream>
#include<stdio>
#include<string>
#include<conio>
using namespace std;
struct books
{
char name[20), author[20];
} a[50];
int main ( )
{
clrscr( );
cout<< “Details of Book No ” << 1 << “\n”;
cout<< “———————\n”;
cout<< ‘Book Name :”<<strcpy(a[0].
name,”Programming “)<<endl;
cout<< “Book Author :”<<strcpy(a[0].
author,”Dromy”)<<endl;
cout<< “\nDetails of Book No ” << 2 <<”\n”;
cout<< ” ——————- \n”;
cout<<- “Book Name :”<<strcpy(a[l].
name,”C++programming” )<<endl;
cout<< “Book Author :”<<strcpy(a[l].
author,”BjarneStroustrup “)< <endl;
cout<<“\n\n”;
cout<< “======================
============================
\n”; ‘
cout<< ” S.No\t| Book Name\t|author\n”;
cout<< “=======================
=============================
for (int i = 0; i < 2; i++)
{
cout<< “\n ” << i + 1 << “\t|” << a[i].name << “\t| ” << a[i],author;
}
cout<< “\n=========-==========
===========================
==”;
return 0;
}
Output

Question 9.
Write the output of the following C++ program
Answer:
#include<iostream>
#include<string>
using namespace std;
struct student
{
introll_no;
char name[10];
long phone_number;
};
int main() .
{
student p1 = {1,”Brown”,123443};
student p2, p3;
p2.roll_no = 2;
strcpy(p2.name,”Sam”);
p2.phone_number = 1234567822;
p3.roll_no = 3;
strcpy(p3.name,”Addy”);
p3.phone_number = 1234567844;
cout<< “First Student” <<endl;
cout<< “roll no : ” << p1.roll_no <<endl;
cout<< “name : ” << p1.name <<endl;
cout<< “phone no ; ” << p1.phone_number <<endl;
cout<< “Second Student” <<endl;
cout<< “roll no : ” << p2.roll_no <<endl;
cout<< “name : ” << p2.name <<endl;
cout<< “phone no : ” << p2.phone_number <<endl;
cout<< “Third Student” <<endl;
cout<< “roll no : ” << p3.roll_no <<endl;
cout<< “name : ” << p3.name <<endl;
cout<< “phone no : ” << p3.phone_number <<endl;
return0;
}
Output

Question 10.
Debug the error in the following program.
Answer:



MODIFIED PROGRAM
#include<iostream.h>
struct PersonRec
{
char lastName[10];
char firstName[10];
int age;
}
Person Rec PeopleArrayType[ 10];
void LoadArray(PeopleRec peop[10]);
void main( )
{
PersonRec people [10];
for (i = 0; i < 10; i++)
{
cout< < people[i].firstName< < ” <<peopie[i].lastName <<setw(10) <<people[i].age;
}
}
LoadArray(PersonRec peop[10])
{
for (int i = 0; i < 10; i++)
{
cout<< “Enter first name: “;
cin<<peop[i].firstName;
cout<< “Enter last name: “;
cin>>peop[i].lastName;
cout<< “Enter age: “;
cin>> peop[i].age;←
}

11th Computer Science Guide Arrays and Structures Additional Questions and Answers

Choose The Correct Answer 1 mark

Question 1.
…………….. is a user-defined which has the combination of data items with different data types.
a) Structure
b) Class
c) Union
d) Array
Answer:
a) Structure

Question 2.
…………………. allows to group of variables of mixed data types together into a single unit.
a) Structure
b) Class
c) Union
d) Array
Answer:
a) Structure

Question 3.
If the elements are of different data types,then ……………… cannot support.
a) Structure
b) Class
c) Union
d) Array
Answer:
d) Array

Question 4.
Structure is declared using the keyword …………………
a) Structure
b) struct
c) Stru
d) STRUCT
Answer:
b) struct

Question 5.
Identify the structure name from the following; struct Student balu;
a) balu
b) struct
c) Student
d) None of these
Answer:
c) Student

Question 6.
Identify the structure variable (object) from the following: struct Student balu;
a) balu
b) struct
c) Student
d) None of these
Answer:
a) balu

Question 7.
How much of memory is required for the object of the following structure in Dev C++.
struct Student
{
long rollno;
int age;
float weight;
}balu, frank;
a) 12 Bytes
b) 8 Bytes
c) 10 Bytes
d) None of these
Answer:
a) 12 Bytes

Question 8.
How much of memory is required for the object of the following structure in Turbo C++.
struct Student
{
long rollno;
int age;
float weight;
}balu, frank;
a) 12 Bytes
b) 8 Bytes
c) 10 Bytes
d) None of these
Answer:
c) 10 Bytes

Question 9.
If the members are pointer types then ……………….. is used to access the structure members.
a) →
b) ←
c) .(dot)
d) None of these
Answer:
a) →

Question 10.
A structure without a …………….. is called an anonymous structure.
a) Name
b) Tag
c) Name/Tag
d) None of these
Answer:
c) Name/Tag

Question 11.
…………………… operator is used to accessing structure member.
a) ::
b) @
c) .(dot)
d) $
Answer:
c) .(dot)

Question 12.
The structure declared within another structure is called a …………….. structure.
a) Nested
b) Group
c) Block
d) None of these
Answer:
a) Nested

Question 13.
……………. structures act as members of another structure.
a) Nested
b) Group
c) Block
d) None of these
Answer:
a) Nested

Question 14.
The members of the child structure can be accessed as …………………….
a) Child structure name. Parent structure name. Member name
a) Parent structure name. Child structure name. Member name
a) Parent structure name. Member name. Child structure name
a) Member name. Parent structure name. Child structure name
Answer:
a) Child structure name. Parent structure name. Member name

Question 15.
A structure variable can be passed to a function in a similar way of passing any argument that is of ……………………. data type.
a) Derived
b) User-defined
c) Built-in
d) None of these
Answer:
c) Built-in

Question 16.
If the structure itself is an argument to a function, then it is called ………………..
a) Call by value
b) Call by Reference
c) Call by Expression
d) None of these
Answer:
a) Call by value

Question 17.
If the reference of the structure is passed as an argument then it is called ……………….
a) Call by value
b) Call by Reference
c) Call by Expression
d) None of these
Answer:
b) Call by Reference

Question 18.
When a structure is passed as an argument to a function using ……………… method, any change made to the contents of the structure variable inside the function to which it is passed do not affect the structure variable used as an argument.
a) Call by value
b) Call by Reference
c) Call by Expression
d) None of these
Answer:
a) Call by value

Question 19.
In ……………….method of passing the structures to functions, any change made to the contents of structure variable inside the function are reflected back to the calling function.
a) Call by value
b) Call by Reference
c) Call by Expression
d) None of these
Answer:
b) Call by Reference

Question 20.
Structures are usually passed by reference method because ……………..
a) It saves the memory space
b) Executes faster
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 21.
Identify the correct statement from the following.
a) A structured object can also be assigned to another structure object only if both the objects are of the same structure type.
b) The structure elements can be initialized either by using separate assignment statements or at the time of declaration by surrounding its values with braces.
c) Array of structure variable can also be created.
d) All the above
Answer:
d) All the above

Very Short Answers (2 Marks)

Question 1.
What is the drawback of an array?
Answer:
In any situation when more than one variable is required to represent objects of uniform data-types, array can be used. If the elements are of different data types, then array cannot support.
If more than one variable is used, they can be stored in memory but not in adjacent locations. It increases the time consumption while searching.

Question 2.
What is the advantage of structure?
Answer:
The structure provides a facility to store different data types as a part of the same logical element in one memory chunk adjacent to each other.

Question 3.
What are global objects?
Answer:
Objects declared along with structure definition are called global objects

Question 4.
Write note on the anonymous structure.
Answer:
A structure without a name/tag is called an anonymous structure.

Example:
struct
{
long rollno;
int age;
float weight;
} student;
The student can be referred to as a reference name to the above structure and the elements can be accessed like a student, roll no, student.age and student.weight

Question 5.
Define Nested structure.
Answer:
The structure declared within another structure is called a nested structure.

Question 6.
Give an example of nested structure.
Answer:
struct Student
{
int age;
float height, weight;
struct dob
{
int date;
char month[4];
int year;
};
}mahesh;

Question 7.
How to access nested member structure?
Answer:
The nested structures act as members of another structure and the members of the child structure can be accessed as
parent structure name. Child structure name. Member name
Example:
mahesh. dob. date

Short Answers 3 Marks

Question 1.
Write the syntax of defining a structure? Give an example.
Answer:
Structure is declared using the keyword ‘struct’. The syntax of creating a structure is given below.
struct structure_name
{
type member-name1;
type member_name2;
} reference_name;
An optional field reference_name can be used to declare objects of the structure type directly.
Example:
struct Student
{
long rollno;
int age;
float weight;
};

Question 2.
How memory is allocated for a structure?
Answer:
Consider the following structure :
struct Student
{
long rollno;
int age;
float weight;
};
In the above declaration of the struct, three variables rollno, age and weight are used. These variables (data element) within the structure are called members (or fields). In order to use the Student structure, a variable of type Student is declared and the memory allocation is shown in the following figure.

Question 3.
How will you refer structure elements?
Answer:
Referencing Structure Elements
Once the two objects of student structure type are declared, their members can be accessed directly.
The syntax for that is using a dot (.) between the object name and the member name. For example, the elements of the structure Student can be accessed as follows:
balu.rollno
frank, rollno
balu.age
frank.age
balu.weight
frank.weight

Explain In Detail 5 Marks

Question 1.
Explain structure assignments in detail.
Answer:
Structure Assignments
Structures can be assigned directly instead of assigning the values of elements individually.
Example:
If Mahesh and Praveen are same age and same height and weight then the values of Mahesh can be copied to Praveen struct Student
{
int age;
float height, weight;
}mahesh;
The age of Mahesh is 17 and the height and weights are 164.5 and 52.5 respectively.The following statement will perform the assignment.
mahesh = {17, 164.5, 52.5};
praveen = mahesh;
will assign the same age, height and weight to Praveen.