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Tamilnadu State Board New Syllabus Samacheer Kalvi 12th Business Maths Guide Pdf Chapter 8 Sampling Techniques and Statistical Inference Miscellaneous Problems Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 12th Business Maths Solutions Chapter 8 Sampling Techniques and Statistical Inference Miscellaneous Problems

Question 1.
Explain the types of sampling.
Solution:
The different types of sampling are

• simple random sampling
• Stratified random sampling and
• Systematic sampling

(i) In simple random sampling, every item of the population has an equal chance for being selected. The sampling can be done with replacement (or) without replacement. A random sampling from a finite population with replacement is equivalent to sampling from an infinite population without replacement. This technique will give useful results only if the population is homogeneous. The following are some of the methods of selecting a random sample.

(a) Use of an unbiased die or coin: If we have to choose between two alternatives, a coin is tossed, and depending on the head or tail course of action is taken. A die can be employed if there are six different alternatives.

(b) Lottery sampling: Here a random sample is selected by identifying each element of the population by means of a card of a pack of uniform cards or (by writing the number on pieces of paper) and to select a required number of cards after thorough mixing of the cards.

(c) Random numbers: Random numbers are formed of ‘random digits’ and arranged in the form of a table having a number of rows and columns. Tippett’s numbers form one such table wherein 40,000 digits were selected at random from census reports and combined by groups of four into 10,000 numbers.

(ii) In stratified random sampling, a population of units is divided into L sub-populations of N₁, N₂, …… N_L. The sub-populations being non-overlapping and mutually exhaustive so that N = N₁ + N₂ + …….. + N_L. Each subpopulation is known as a stratum. If we select n₁, n₂, ……. n_l items, respectively, from these strata, we get a stratified sample. If a simple random sample is taken from each stratum, the whole procedure is referred to as stratified random sampling.

(iii) Systematic sampling is a form of restricted random selection which is highly useful in surveys concerning enumerable population. In this method, every member of the population is numbered in serial order and every ith element, starting from any of the first items is chosen. For example, suppose we require a 5% sample of students from a college where there are 2000 students, we select a random number from 1 to 20. If it is 12, then our sample consists of students with numbers 12, 32, 52, 72, …… 1992.

Question 2.
Write a short note on sampling distribution and standard error.
Solution:
sampling distribution:
The sampling distribution of a statistic is the frequency distribution which is formed with various values of a statistic computed from different samples of the same size drawn from the same population.

For instance, if we draw a sample a size n from a given finite population of N, then the total number of possible samples is Nc_n = \(\frac { N! }{n!(N-n)!}\) = k(say)

Standard Error:
The standard deviation of the sampling distribution of a statistic is known as its standard Error abbreviated as S.E. The standard error (S.E) of some of the well-known statistics, for large samples, are given below, where n is the sample size, σ² is the population variance.

Question 3.
Explain the procedures of testing of hypothesis
Solution:
The following are the steps involved in hypothesis testing problems:
1. Null hypothesis: Set up the null hypothesis H₀

2. Alternative hypothesis: Set up the alternative hypothesis. This will enable us to decide whether we have to use two-tailed test or single-tailed test (right or left tailed)

3. Level of significance: Choose the appropriate level of significance (a) depending on the reliability of the estimates and permissible risk. This is to be fixed before the sample is drawn, i.e., a is fixed in advance.

4. Test statistic: Compute the test statistic
Z = \(\frac { t-E(t) }{\sqrt{var(t)}}\) = \(\frac { t-E(t) }{S.E(t)}\) N(0, 1) as n → ∞

5. Conclusion: We compare the computed value of Z in step 4 with the significant value or critical value or table value Zα at the given level of significance.
(i) If |Z | < Zα i.e., if the calculated value is less than the critical value we say it is not significant. This may due to fluctuations of sampling and sample data do not provide us sufficient evidence against the null hypothesis which may therefore be accepted.

(ii) If |Z |> Zα i.e., if the calculated value of Z is greater than critical value Zα then we say it is significant and the null hypothesis is rejected at the level of significance α.

Question 4.
Explain in detail the test of significance for a single mean.
Solution:
Let xi, (i = 1, 2, 3, …, n) is a random sample of size from a normal population with mean µ and variance σ² then the sample mean is distributed normally with mean and variance
\(\frac { σ^2 }{n}\), i.e \(\bar { x }\) N(µ, \(\frac { σ^2 }{n}\))

Thus for large samples, the standard normal variate corresponding to \(\bar { x }\) is
Z = \(\frac {\bar { x } -µ }{\frac{σ}{√n}}\) N (0, 1)

Under the null hypothesis that the sample has been drawn from a population with mean and variance σ², i.e., there is no significant difference between the sample mean (\(\bar { x }\)) and the population mean (α), the test statistic (for large samples) is:
Z = \(\frac {\bar { x } -µ }{\frac{σ}{√n}}\)

Question 5.
Determine the standard error of proportion for a random sample of 500 pineapples was taken from a large consignment and 65 were found to be bad?
Solution:
sample size n = 500
No. of bad pine apples = 65
sample proportion = P = \(\frac { 65 }{500}\) = 0.13
Q = 1 – p ⇒ Q = 1 – 0.13
∴ Q = 0.87
The S.E for sample proportion is given by
S.E = \(\sqrt{\frac { PQ }{N}}\) = \(\sqrt{\frac { (0.13)(0.87) }{500}}\)
= \(\sqrt{\frac { 0.1131 }{500}}\) = \(\sqrt{0.0002262}\)
= 0.01504
∴ S.E = 0.015
Hence the standard error for sample proportion is S.E = 0.015

Question 6.
A sample of 100 students are drawn from a school The mean weight and variance of the sample are 67.45 kg and 9 kg respectively find (a) 95% and (b) 66% confidence intervals for estimating the mean weight of the students.
Solution:
sample size n = 100
The sample mean = \(\bar { x }\) = 67.45
The sample variance S² = 9
The sample standard deviation S = 3
S.E = \(\frac { S }{√n}\) = \(\frac { 3 }{\sqrt{100}}\) = \(\frac { 3 }{10}\) = 0.3

(a) The 95% confidence limits for µ are given by
\(\bar { x }\) – z_{\(\frac { α }{2}\)} S.E < µ < \(\bar { x }\) + z_{\(\frac { α }{2}\)} S.E
67.45 – (1.96 × 0.3) ≤ µ ≤ 67.45 + (1.96 × 0.3) 67.45 – 0.588 ≤ µ ≤ 67.45 + 0.588
66.862 ≤ µ ≤ 68.038
The confidential limits is (66.86, 68.04)

(b) The 99% confidence limits for estimating µ are given by
\(\bar { x }\) – z_{\(\frac { α }{2}\)} S.E ≤ µ ≤ \(\bar { x }\) + z_{\(\frac { α }{2}\)} S.E
67.45 – (2.58 × 0.3) ≤ µ ≤ 67.45 + (2.58 × 0.3)
67.45 – 0.774 ≤ µ ≤ 67.45 + 0.774
66.676 ≤ µ ≤ 68.224
∴ The 99% confidence limits is (66.68, 68.22)

Question 7.
The mean I.Q of a sample of 1600 children was 99. it is likely that this was a random sample from a population with a mean I.Q 100 and standard deviation of 15? (Test at 5% level of significance)
Solution:
sample size n = 1600
\(\bar { x }\) = 99
sample mean
Population mean µ = 100
population S.D σ = 15
under the Null hypothesis H₀ : µ = 100
Alternative hypothesis H₁ : µ = 100 (two tails)
Level of significance µ = 0.05

z = -2.666
z = -2.67
Calculated value |z| = 2.67
critical value at 5% level of significance is
z_{\(\frac { α }{2}\)} = 1.96
Inference:
Since the calculated value is greater than table value i.e z ⇒ z_{\(\frac { α }{2}\)} at 5% level of significance, the null hypothesis is rejected. Therefore we conclude that the sample mean differs, significantly from the population mean.

Tamilnadu State Board New Syllabus Samacheer Kalvi 12th Business Maths Guide Pdf Chapter 9 Applied Statistics Ex 9.2 Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 12th Business Maths Solutions Chapter 9 Applied Statistics Ex 9.2

Question 1.
Define Index Number.
Solution:
“An Index Number is a device which shows by its variations the Changes in a magnitude which is not capable of accurate measurements in itself or of direct valuation in practice”. – Wheldon

“An Index number is a statistical measure of fluctuations in a variable arranged in the form of a series and using a base period for making comparisons” – Lawrence J Kaplan

Question 2.
State the uses of Index Number.
Solution:

1. The index number is an important tool for formulating decision and management p policies.
2. It helps in studying the trends and tendencies.
3. It determines the inflation and deflation in an Economy.

Question 3.
Mention the classification of Index Number.
Solution:
Classification of Index Numbers:
Index number can be classified as follows:

1. Price Index Number: It measures the general changes in the retail or wholesale price level of a particular or group of commodities.
2. Quantity Index Number: These are indices to measure the changes in the number of goods manufactured in a factory.
3. Cost of living Index Number: These are intended to study the effect of change in the price level on the cost of living of different classes of people.

Question 4.
Define Laspeyre’s Price index number.
Solution:
Laspeyres Price index number
P\(_{ 01 }^{L}\) ⥪ \(\frac { Σp_1q_0 }{Σp_0q_0}\) × 100
where P₁ = Current year price
p₀ = base year price
q₀ = base year quantity

Question 5.
Explain Paasche’s price index number.
Solution:
Paasches price index number
P\(_{ 01 }^{L}\) = \(\frac { Σp_1q_1 }{Σp_0q_1}\) × 100
where P₁ = current year price
q₁ = current year quantity
p₀ = base year price
q₀ = base year quantity

Question 6.
Write note on Fisher’s price index number.
Solution:
Fishers price index number
P^F = \(\sqrt { P^L×P^P}\)
P\(_{ 01 }^{F}\) = \(\sqrt { \frac{Σp_1p_0×Σp_1q_1}{Σp_0q_0×Σp_0q_1}}\) × 100
where P₁ = current year price
q₁ = current year quantity
p₀ = base year price
q₀ = base year quantity

Question 7.
State the test of adequacy of index number.
Solution:
There are two tests which are used to test the adequacy for an index number. The two tests are as follows
(i) Time Reversal Test
(ii) Factory Reversal Test

Question 8.
Define Time Reversal Test.
Solution:
It is an important test for testing the consistency of a good index number. This test maintains time consistency by working both forward and backward with respect to time (here time refers to base year and current year). Symbolically the following relationship should be satisfied. P₀₁ × p₁₀ = 1

Fisher’s index number formula satisfies the above relationship
P\(_{ 01 }^{F}\) = \(\sqrt { \frac{Σp_1p_0×Σp_1q_1}{Σp_0q_0×Σp_0q_1}}\)

when the base year and current year are interchanged, we get
P\(_{ 10 }^{F}\) = \(\sqrt { \frac{Σp_0q_1×Σp_0q_0}{Σp_1q_1×Σp_1q_0}}\)
P\(_{ 01 }^{F}\) × P\(_{ 10 }^{F}\) = 1

Question 9.
Explain factor reversal test.
Solution:
This is another test for testing the consistency of a good index number. The product of price index number and quantity index number from the base year to the current year should be equal to the true value ratio. That is, the ratio between the total value of current period and total
value of the base period is known as true value ratio. Factor Reversal Test is given by,

where P₀₁ is the relative change in price
Q₀₁ is the relative change in quantity.

Question 10.
Define true value ratio.
Solution:
The ratio between the total value of the current period and the total value of the base period is known as the true value ratio.
(i.e) true value ratio = \(\frac{\sum p_{1} q_{1}}{\sum p_{0} q_{0}}\)

Question 11.
Discuss the Cost of the Living Index Number.
Solution:
Cost of living index numbers are generally designed to represent the average change over time in the prices paid by the ultimate consumer for a specified quantity of goods and services cost of living index number is also known as the consumer price index number.

It is well known that a given change in the level of prices (retail) affects the cost of living of different classes of people in different manners. The general index number fails to reveal this. Therefore it is essential to construct a cost of living index number which helps us in determining the effect of rise and fall in prices on different classes of consumers living in different areas.

Question 12.
Define family budget method.
Solution:
Family Budget Method:
In this method, the weights are calculated by multiplying prices and quantity of the base year.
(i.e.) V = Σp₀q₀. The formula is given by,
Cost of Living Index Number = \(\frac{\sum \mathrm{PV}}{\sum \mathrm{V}}\)
where P = \(\frac{p_{1}}{p_{0}} \times 100\) is the price relative
V = Σp₀q₀ is the value relative

Question 13.
State the uses of cost of Living Index Number.
Solution:
(i) It indicates whether the real wages of workers are rising or falling for a given time.
(ii) It is used by the administrators for regulating dearness allowance or grant of bonus to the workers.

Question 14.
Calculate by a suitable method, the index number of price from the following data:

Solution:

Question 15.
Calculate price index number for 2005 by (a) Laspeyre’s (b) Paasche’s method

Solution:

Question 16.
Calculate price index number for 2005 by (a) Laspeyre’s (b) Paasche’s method

Solution:

Question 17.
Using the following data, construct Fisher’s Ideal index and show how it satisfies Factor Reversal Test and Time Reversal Test?

Solution:

Question 18.
Using the following data, construct Fisher’s Ideal index and show how it satisfies Factor Reversal Test and Time Reversal Test?

Solution:

Question 19.
Calculate Fisher’s index number to the following data. Also show that it satisfies Time Reversal Test.

Solution:

Question 20.
Th following are the group index numbers and the group weights of an average working class family’s budget. Construct the cost of living index number:

Solution:

Question 21.
Construct the cost of living Index number for 2015 on the basis of 2012 from the following data using family budget method.

Solution:

Question 22.
Calculate the cost of living index by aggregate expenditure method:

Solution:

Tamilnadu State Board New Syllabus Samacheer Kalvi 12th Business Maths Guide Pdf Chapter 7 Probability Distributions Ex 7.2 Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 12th Business Maths Solutions Chapter 7 Probability Distributions Ex 7.2

Question 1.
Define possion distribution.
Solution:
Poisson distribution was derived in 1837 by a French Mathematician Simeon D. Poisson.
A random variable X is said to follow a Poisson distribution with parameter X if it assumes only non-negative values and its probability mass function is given by

Question 2.
Write any 2 examples for possion distribution
Solution:
Examples of Poisson distribution are given by

• The number of printing mistakes per page in a textbook.
• A number of lightning per second.
• The number of bacteria in one cubic centimetre.

Question 3.
Write the condition for which the Poisson distribution is limiting case of binomial distribution
Solution:
Poisson distribution is a limiting case of binomial distribution under the following conditions:
(i) n, the number of trials is indefinitely large i.e n → ∞
(ii) p, the constant probability of success in each trial is very small, i.e. p → 0.
(iii) np = λ is finite. Thus p = \(\frac { λ }{n}\) and q = 1 – (\(\frac { λ }{n}\))
where λ, is a positive real number.

Question 4.
Derive the mean and variance of the Poisson distribution.
Solution:
Derivation of Mean and variance of Poisson distribution

Variance (X) = E(X²) – E(X)²

Variance (X) = E(X²) – E(X)²
= λ² + λ – (λ)²
= λ

Question 5.
Mention the properties of Poisson distribution.
Solution:

1. Poisson distribution is the only distribution in which the mean and variance are equal.
2. The probability that an event occurs in a given time, distance, area, or volume is the same.

Question 6.
The mortality rate for a certain disease is 7 in 1000. What is the probability for just 2 deaths on account of this disease in a group of 400? Give e^(-2.8) = 0.06
Solution:
Since the mortality rate for a certain disease in 7 in loop
∴ p = \(\frac { 7 }{1000}\) and n = 400
The value of mean A = λp = 400 × \(\frac { 7 }{1000}\)
∴ λ = 2.8
Let x be a random variable following
distribution with p(x) = \(\frac { e^{-λ}λ^x }{x!}\)
∴ the distribution is p(x = 2) = \(\frac { e^{-2-8}(2.8)^2 }{2!}\)
\(\frac { 0.06×7.84 }{2}\)
= 0.2352

Question 7.
Mention the properties of Poisson distribution.
Solution:
Given p = \(\frac{5}{100}\) = 0.05 and n = 120
⇒ λ = np = (0.05) (120) = 6
Thus X is a Poisson random variable with P (X = x) = \(\frac{e^{-6} 6^{x}}{x !}\)
We want P (no defective bulb) = P (X = 0)
= \(\frac{e^{-6} 6^{0}}{0 !}\)
= e^-6
= 0.0025 (Using exponent table)
Thus the probability that a sample of 120 bulbs will not contain any defective bulb is 0.0025.

Question 8.
A car hiring firm has two cars. The demand for cars on each day is distributed as a Poisson variate, with a mean of 1.5. Calculate the proportion of days on which
(i) Neither car is used
(ii) Some demand is refused
Solution:
In a poisson distribution n=2
mean λ = 1.5
x follows poison distribution
With in p(x) = \(\frac { e^{-λ}λ^x }{x!}\)
(i) p(neither car is used) = p(x = 0)
\(\frac { e^{-1.5}(1.5)^0 }{0!}\) = e^-1.5
= 0.2231

(ii) p(some demand is refused) = p(x > 2)

= 1 – 0.2231 [1 + 1.5 + 1.125]
= 1 – 0.2231 [3.625]
= 1-0.8087
= 0.1913

Question 9.
The average number of phone calls per minute into the switchboard of a company between 10.00 am and 2.30 pm is 2.5. Find the probability that during one particular minute there will be (i) no phone at all (ii) exactly 3 calls (iii) atleast 5 calls
Solution:
The average number of phone cells per minute into the switch board of a company is λ = 2.5
x follows poisson distribution with

(iii) p(atleast 5 calls) = p(x ≥ 5)
= p(x = 5) + p(x = 6) + …………..
= 1 – p(x < 5)

Question 10.
The distribution of the number of road accidents pre-day in a city is Poisson with mean 4. Find the number of days out of 100 days when there will be (i) no accident (ii) atleast 2 accidents and (iii) at most 3 accidents.
Solution:
In a possion distribution
mean λ = 4
n = 100
x follows possion distribution with
p(x) = \(\frac { e^{-λ}λ^x }{x!}\) = \(\frac { e^{-4}(4)^x }{x!}\)
(i) p(no accident) = p(x = 0)
= \(\frac { e^{-4}(4)^0 }{0!}\) = e^-4 = 0.0183
out of 100 days there will be no accident
= n × p(x = 0)
= 100 × 0.0183 = 1.83
= 2 days (approximately)

(ii) p(atleast 2 accidents)
= p(x ≥ 2)
= p(x = 2) + p(x = 3) + p(x = 4) + …………
= 1 – p(x < 2)
= 1 – [p(x = 0) + p(x = 1)]
= 1 – [\(\frac { e^{-4}(4)^0 }{0!}\) + \(\frac { e^{-4}(4)^1 }{1!}\)]
= 1 – e^-4 [l + 4]
= 1 – 0.0183(5) = 1 – 0.0915
= 0.9085
= Out of 100 days there will be atleast 2 accidents = n × p(x ≥ 2)
= 100 × 0.9085
= 90.85
= 91 days (approximately)

(iii) p(atmost 3 accident) = p(x ≤ 3)
= p(x = 0) + p(x = 1) + p(x = 2) + p(x = 3)

out of 100 days there will be at most 3 acccident = n × p(x ≤ 3)
= 100 × 0.4331
= 43.31
= 43 days(approximately)

Question 11.
Assuming that a fatal accident in a factory during the year is 1/1200/ calculate the probability that in a factory employing 300 workers there will be atleast two fatal accidents in year, (given e^-0.25 = 0.7788 Solution:
Let p be the probability of a fatal accident in a factory during the yeart
p = \(\frac { 1 }{1200}\) and n = 300 1200
λ = np = 300 × \(\frac { 1 }{1200}\) = \(\frac { 1 }{4}\)
λ = 0.25
x follows poison distribution with
p(x) = \(\frac { e^{-λ}λ^x }{x!}\) + \(\frac { e^{-0.25}(0.25) }{x!}\)
p(atleasttwo fatal accidents) = p(x ≥ 2)
= p(x = 2) + p(x = 3) + p(x = 3) + p(x = 4) + ……….
= 1 – p(x < 2)
= 1 – {p(x = 0) + p(x = 1)}
= 1 – 0.7788 [1 + 0.25]
= 1 – 0.7788(1.25)
= 1 – 0.9735 = 0.0265
∴ p(x ≥ 2) = 0.0265

Question 12.
The average number of customers, who appear in a counter of a certain bank per minute is two. Find the probability that during a given minute (i) No customer appears (ii) three or more customers appear.
Solution:
The average number of customers ,who appear in a counter of a certain bank per minute = 2
∴ λ = 2
x follows poisson distribution with
p(x) = \(\frac { e^{-λ}λ^x }{x!}\)
x follows poisson distribution with p(x) = \(\frac { e^{-λ}λ^x }{x!}\)
(i) p(no customber appears) = p(x = 0)
= \(\frac { e^{-2}(2)^0 }{0!}\) = e^-2
= 0.1353

(ii) p(three or more customers appears) = p(x ≥ 3)
= p(x = 3) + p{x = 4) + p(x = 5) + ……
= 1 – p(x < 3)
= 1 – {p(x = 0) + p(x = 1) + p(x = 2)}

= 1 – 2^-2 [1 + 2 + 2]
= 1 – 0.1353(5)
= 1 – 0.6765
= 0.3235

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Tamilnadu State Board New Syllabus Samacheer Kalvi 12th Business Maths Guide Pdf Chapter 7 Probability Distributions Ex 7.1 Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 12th Business Maths Solutions Chapter 7 Probability Distributions Ex 7.1

Question 1.
Define Biomial distribution.
Solution:
Binomial distribution was discovered by James Bernoulli (1654-1705) in the year 1700.
A random variable X is said to follow binomial distribution with parameter n and p, if it assumes only non-negative value and its probability mass function in given by

Question 2.
Define Bernoulli trials.
Solution:
A random experiment whose outcomes are of two types namely success S and failure F, occurring with probabilities p and q, is called a Bernoulli trial.
Example 1, Tossing of a coin (Head or Tail)
Example 2, Writing an exam (Pass or Fail)

Question 3.
Derive the mean and variance of binomial distribution
Solution:
Derivation of the Mean and Variance of Binomial distribution:
The mean of the binomial distribution

= np(q + p)n – 1 [since p + q = 1]
= np
E(X) = np
The mean of the binomial distribution is np.
Var(X) = E(X²) – E(X²)

= n(n – 1)p²(q + p)(n – 2) + np
n(n – 1 )p² + np
Variance = E(X²) – [E(X)]²
= n²p² – np² + np – n²p²
= np(1 – p) = npq
Hence, the mean of the BD is np and the Variance is npq.

Question 4.
Write down the condition for which the binomial distribution can be used.
Solution:
The binomial distribution can be used under the following conditions:

• The number of trials (or) observations ‘n’ is fixed (finite).
• Each observation is independent of the other.
• In every trial, there are only two possible outcomes – success or failure.
• The probability of success ‘p’ is the same for each outcome.

Question 5.
Mention the properties of the binomial distribution.
Solution:
Properties of Binomial distribution
1. Binomial distribution is symmetrical if p = q = 0.5, It is skew-symmetric if p ≠ q. It is positively skewed if p < 0.5 and it is negatively skewed it p > 0.5.
2. For Binomial distribution, variance is less than mean
Variance npq = (np) q < np

Question 6.
If 5% of the items produced turn out to be defective, then find out the probability that out of 10 items selected at random there are
(i) exactly three defectives
(ii) atleast two defectives
(iii) exactly 4 defectives
(iv) find the mean and variance.
Solution:
Probability of getting a defective item

In binomial distribution
p(X = x) = nC_xp^xq^n-x

Let x = (19)²
log x = 7 log(19)⁷
= 7 log 19
= 7 × 1.2788
= 8.9516
x = Antilog 8.956
= 8.945 × 10⁸
ut y = (20)¹⁰
log y = (10) log 20
= 10 × 1.3010
= 13.010
y = Anti log 13.010
= 1.023 × 10³

(ii) p(atleast two defectives)
= p(x ≥ 2)
= p(x = 2) = p(x = 3) + ………….. + p(x = 10)
= 1 – p(x < 2)
= 1 – {p(x = 0) + p(x = 1)}

Let x = (19)⁹
log x = 9 log 19
= 9 × 1.2788
= 11.5092
x = Antilog 11.5092
= 3.229 × 1011

(iii) p(extactly 4 defectives) = p(X = 4)

Let x = (19)⁶
log x = 6 log 19
= 6 × 1.2788
log x = 7.66728
Antilog (7.66728)
x = 4.648 × 10⁷

(iv) mean E(x) = np
= 10 × \(\frac { 1 }{20}\) = \(\frac { 1 }{2}\) = 0.5
Varaince = npq
= 10 × \(\frac { 1 }{20}\) = \(\frac { 19 }{20}\) = \(\frac { 19 }{40}\) = 0.475

Question 7.
In a particular university 40% of the students are having news paper reading habit. Nine university students are selected to find their views on reading habit. Find the probability that
(i) none of those selected have news paper reading habit
(ii) all those selected have news paper reading habit
(iii) atleast two third have news paper reading habit.
Solution:
let p to the probability of having newspaper reading habit
p = \(\frac { 40 }{100}\) = \(\frac { 2 }{5}\)
q = 1 – p = 1\(\frac { 2 }{5}\) = \(\frac { 5-2 }{5}\) = \(\frac { 3 }{5}\) and n = 9
In the binomial distribution p(x = 4) = nc_x p^xq^n-r
The binomial distribution P(x) = 9c_x (\(\frac { 2 }{5}\))^x (\(\frac { 3 }{5}\))^9-x

(i) p(none of those selected have newspaper reading

(ii) P(all those selected have newspaper reading habit)

(iii) p(at least two third have newspaper reading habit)

Question 8.
In a family of 3 children, what is the probability that there will be exactly 2 girls?
Solution:
let p be the probability of getting a girl child= 1/2 q = 1 – p ⇒ = 1 – 1/2
∴ q = \(\frac { 1 }{2}\) and n = 3
In a binomial distibution
p(x = x) nc_x p^xq^n-x
p(exactly 2 girls) p(x = 2)

Question 9.
Defects in yarn manufactured by a local mill can be approximated by a distribution with a mean of 1.2 defects for every 6 metres of length. If lengths of 6 metres are to be inspected, find the probability of less than 2 defects.
Solution:
Given n = 6
mean np = 1.2
⇒ 6p = 1.2
p = \(\frac { 1.2 }{6}\) p = 0.2 (or) p = \(\frac { 1 }{5}\)
q = 1 – p = 1 – \(\frac { 1 }{5}\)
∴ q = \(\frac { 4 }{5}\)
The binomial distribution
p(x) = 6C_x (0.2)^x(0.8)^6-x
p(x < 2) = p(x = 0) + p(x = 1)

Question 10.
If 18% of the bolts produced by a machine are defective, determine the probability that out of the 4 bolts chosen at random
Solution:
Let X be the random variable denoting the number of defective bolts.
The probability of defective bolts p = \(\frac{18}{100}\) = 0.18 ⇒ q = 0.82.
Also n = 4
The p.m.f is P (X = x ) = \(^{4} \mathrm{C}_{x}(0.18)^{x}(0.82)^{4-x}\)
(i) P (exactly one defective) = P(X = 1)
= \(^{4} \mathrm{C}_{1}(0.18)^{1}(0.82)^{3}\)
= 4 (0.18) (0.82)³
= 0.3969
(ii) P (no defective) = P(X = 0)
= \(^{4} \mathrm{C}_{0}(0.18)^{0}(0.82)^{4}\)
= (0.82)⁴
= 0.45212
(iii) P (atmost 2 defective) = P(X ≤ 2)
= P(X = 2) + P(X = 1) + P(X = 0)
= \(^{4} \mathrm{C}_{2}\) (0.18)² (0.82)² + 0.3969 + 0.45212
= 0.1307 + 0.3969 + 0.45212
= 0.97972

Question 11.
If 18% of the bolts produced by a machine are defective, determine the probability that out of the 4 bolts chosen at random
(i) exactly one will be defective
(ii) none will be defective
(iii) atmost 2 will be defective
Solution:
p = 0.09 = \(\frac { 9 }{100}\)
q = 1 – p ⇒ q – 1 – \(\frac { 9 }{100}\)
q = \(\frac { 100-9 }{100}\)
q = \(\frac { 91 }{100}\)
In a binomial distribution p(x = x) = nc_xp^xq^n-x
p(atleast one success) = p(x ≥ 1)

Taking log on both sides log ≤ (0.66) ≤ n log(0.91)
∴ n ≥ log \(\frac { log(0.66) }{log(0.91)}\)
n ≥ 5
∴ 5 or more trials are needed

Question 12.
Among 28 professors of a certain department, 18 drive foreign cars and 10 drive local made cars. If 5 of these professors are selected at random, what is the probability that atleast 3 of them drive foreign cars?
Solution:
Let p be the probability of foreign cars driven by the professors
p = \(\frac { 18 }{28}\) = \(\frac { 9 }{14}\)
Let q be the probability of local made cars driv¬en by the professors
q = \(\frac { 10 }{28}\) = \(\frac { 5 }{14}\)
and n = 5
The binomial distribution p(x = x) = nc_xp^xq^n-x

Question 13.
Out of 750 families with 4 children each, how many families would be expected to have (i) atleast one boy (ii) atmost 2 girls (iii) and children of both sexes? Assume equal probabilities for boys and girls?
Solution:
Assume equal probabilities for boys girls let p be the probability of having a boy Let x be the random variable for getting either a boy or a girl
∴ p = \(\frac { 1 }{2}\) and q \(\frac { 1 }{2}\) and n = 4
In binomial distribution p(x = 4) = nc_xp^xq^n-x
Here the binomial distribution is p(X= x)

= 1 – 0.0625
= 0.9375
for 750 families (p ≥ 1) = 750 × 0.9375
= 703.125
= 703(approximately)

(ii) p(almost 2 girls) = p(x ≤ 2)
= p(x = 0) = p(x = 1) + p(x = 2)

For 750 families p(x ≤ 2) = 0.6875 × 750
= 515.625
= 516 (approximately)

(iii) p(children of both sexes) = p(x = 1) + p(x = 2)p(x = 3)

= 0.875 x 750
For 750 families p(x = 2) = 0.875 × 750
= 656.25
= 656 (approximately)

Question 14.
Forty percent of business travellers carry a laptop. In a sample of 15 business travelers,
Solution:
Given n = 5
p = \(\frac { 40 }{100}\) = \(\frac { 2 }{5}\)
q = 1 – p = 1 – \(\frac { 2 }{5}\) \(\frac { 5-2 }{5}\) = \(\frac { 3 }{5}\)
The binomial distributionp (X = x) = 15c_x (\(\frac { 2 }{5}\))^x (\(\frac { 3 }{5}\))^15-x
(i) p(probability that 3 will have a laptop) = p(x = 3)

(ii) p(12 of the traels will not have a laptop)
= 1 – p(x = 12)
= 1 – 15c₁₂ (\(\frac { 2 }{5}\))¹² (\(\frac { 3 }{5}\))^15-12

(iii) p(at least three of the travelers have a laptop)
= p(x ≥ 3)
p(x ≥ 3) = 1 – p (x < 3)
= 1 – [p(x = 0) + p(x = 1) + p(x = 2)]
p(x < 3) = p(x = 0) + p(x = 1) + p(x = 2)

Question 15.
A pair 5f dice is thrown 4 times. If getting a doublet is considered a success, find the probability of 2 successes.
Solution:
In a throw of a pair dice the doublets are (1, 1),(1, 2) (3, 3),(4, 4),(5, 5),(6, 6)
probability of getting a doublet p = \(\frac { 6 }{36}\) = \(\frac { 1 }{6}\)
⇒ q = 1 – q = \(\frac { 5 }{6}\) and n = 4 is given
The probability of success = \(\left[\begin{array}{l}
4 \\
x
\end{array}\right]\) [latex]\frac { 1 }{6}[/latex]^x [latex]\frac { 5 }{6}[/latex]^4-x
Therefore the probability of 2 success are

Question 16.
The mean of a binomial distribution is 5 and the standard deviation is 2. Determine the distribution.
Solution:
In a binomial distribution
mean np = 5 → (1)
Standard deviation \(\sqrt { npq}\) = 2
squaring on body sides
npq = 4 → (2)

n = 5 × 5 ⇒ n = 25
∴ the binomial distribution is
P(X = x) = nc_xp^xq^n-x
(i.e) p(X = x) = \(\left[\begin{array}{l}
25 \\
x
\end{array}\right]\) (\(\frac { 1 }{5}\))^x (\(\frac { 4 }{5}\))^(25-x)

Question 17.
Determine the binomial distribution for which the mean is 4 and variance 3. Also find P(X = 15)
Solution:
In a binomial distribution
mean np = 4 → (1)
variance npq = 3 → (2)

n = 4 × 4 ⇒ n = 16
The binomial distribution is p(X = x)nc_xp^xq^n-x

Question 18.
Assume that a drug causes a serious side effect at a rate of three patients per one hundred. What is the probability that atleast one person will have side effects in a random sample of ten patients taking the drug?
Solution:
Here n = 10

= 0.5344

Question 19.
Consider five mice from the same litter, all suffering from Vitamin A deficiency. They are fed a certain dose of carrots. The positive reaction means recovery from the disease.
Assume that the probability of recovery is 0.73. What is the probability that atleast 3 of the 5 mice recover.
Solution:
n = 5
Let probability of recovery p = 0.73
q = 1 – p = 1 – 0.73
∴ q = 0.27
The binomial distribution is
p (x = x) = nC_xp^xq^n-x
p(x = x) = 5C_x(0.73)^x(0.27)^5-x
p(atleast 3 of the 5 mice recover) = p(x ≥ 3)
= p(x = 3) + p(x = 4) + p(x = 5)
= 5C₃ (0.73)³(0.27)^5-3 + 5C₄ (0.73)⁴ (0.27)^5-4 + 5C₅ (0.73)⁵ (0.27)^5-5
5C₂ (0.73)³ (0.27)² + 5c₁ (0.73)⁴ (0.27)¹ + 5c₀(0.73)⁵(0.27)°
[\(\frac { 5×4 }{1×2}\) × 0.389017 × 0.0729] + [5 × 0.28398241 × 0.27] + (1 × 0.2073071593 × 1)
= 0.283593393 + 0.3833762535 + 0.2073071593
= 0.2836 + 0.3834 + 0.2073
= 0.8743

Question 20.
Consider five mice from the same litter, all suffering from Vitamin A deficiency. They are fed a certain dose of carrots. The positive reaction means recovery from the disease. Assume that the probability of recovery is 0.73. What is the probability that atleast 3 of the 5 mice recover.
Solution:
Success = 2 × fails
p = 2q ⇒ p = 2(1 – p)
p = 2 – 2p ⇒ p + 2p = 2
3p = 2 and p = 2/3
q = 1 – p = 1 – 2/3
q = 1/3 and n = 5
The binomial destribution is
p (X = x) = nC_xp^xq^n-x
= 5C(2/3)^x (1/3)
(i) p(three successes) = p(x = 3)

Tamilnadu State Board New Syllabus Samacheer Kalvi 12th Business Maths Guide Pdf Chapter 8 Sampling Techniques and Statistical Inference Ex 8.1 Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 12th Business Maths Solutions Chapter 8 Sampling Techniques and Statistical Inference Ex 8.1

Question 1.
What is the population?
Solution:
A population is a set of similar items or events which is of interest for some question or experiment. A population can be specific or vague. Examples of population defined vaguely include the number of newborn babies in Tamil Nadu, the total number of tech startups in India, the average height of all exam candidates, mean weight of taxpayers in Chennai etc. Examples of population defined specifically include a number of fans produced in a particular factory, the number of students in a class, the number of boys and girls in a tuition centre etc.

Question 2.
What is the sample?
Solution:
A selection of a group of observation/individuals/population in such a way that is represents the population is called a sample.

Question 3.
What is a statistic?
Solution:
A statistic is used to estimate the value of a population parameter. For instance, we selected a random sample of 100 students from a school with 1000 students. The average height of the sampled students would be an example of a statistic. Examples, sample variance, sample quartiles, sample percentiles, sample moments, etc.

Question 4.
Define parameter.
Solution:
Parameter: The statistical constants of the population like mean (µ), variance (σ²) are referred to as population parameters.

Question 5.
What is the sampling distribution of a statistic?
Solution:
Sampling distribution of a statistic is the frequency distribution which is formed with various of a statistic computed from different samples of the same size drawn from the same population.

Question 6.
What is a standard error?
Solution:
The standard error (S.E) of a statistic is the standard deviation of its sampling distribution. If the parameter or the statistic is the mean, it is called the standard error of the mean (SEM). The standard error provides a rough estimate of the interval in which the population parameters are likely to fall.

Question 7.
Explain in detail about simple random sampling with a suitable example.
Solution:
In this technique, the samples are selected in such a way that each and every unit in the population has an equal and independent chance of being selected as a sample. Simple random sampling may be done, with or without replacement of samples selected. In a simple random sampling with replacement, there is a possibility of selecting the same sample any number of times.

So, simple random sampling without replacement is followed. Thus in simple random sampling from a population of N units, the probability of drawing any unit at the first draw is \(\frac { 1 }{N}\), the probability of drawing any unit in the second draw from among the available (N – 1) units is \(\frac { 1 }{(N-1)}\), and so on.

For example, if we want to select 10 students, out of 100 students, then we must write the names/roll number of all the 100 students on slips of the same size and mix them, then we make a blindfold selection of 10 students. This method is called unrestricted random sampling because units are selected from the population without any restriction. This method is mostly used in lottery draws. If the population or universe is infinite, this method is inapplicable.

Question 8.
Explain the stratified random sampling with a suitable example.
Solution:
In stratified random sampling, first divide the population into subpopulations, which are called strata. Then,the samples are selected from each of the strata through random techniques. The collection of all the samples from all strata gives the stratified random samples.

When the population is heterogeneous or different segments or groups with respect to the variable or characteristic understudy, then stratified Random sampling methods are studied. First, the population is divided into a homogeneous number of sun-groups of strata before the sample is drawn. A sample from each stratum at random. The following steps are involved in selecting a random sample in a stratified random sampling method.

(a) The population is divided into different classes so that each stratum will consist of more or less homogeneous elements. The strata are so designed that they do not overlap each other.

(b) After the population is stratified, a sample of a specified size is drawn at random from each stratum using the Lottery Method or table of random number method.

Question 9.
Explain in detail systematic random sampling with example.
Solution:
In systematic sampling, randomly select the first sample from the first k units. Then every kth member, starting with the first selected sample, is included in the sample.

Systematic sampling is a commonly used technique if the complete and up-to-date list of the sampling units is available. We can arrange the items in numerical, alphabetical, selecting the first at random, the rest being automatically selected according to some pre-determined pattern. A systematic is formed by selecting every item from the population, where k refers to the sample interval. The sampling interval can be determined by divided the size of the population by the size of the sample to be chosen.

That is K = \(\frac { N }{n}\), where k is an integer.
k = sampling interval, size of the population, sample size
Procedure for selection of samples by systematic sampling method

(i) If we want to select a sample of 10 students from a class of 100 students,the sampling interval is Calculated as k = \(\frac { N }{n}\) = \(\frac { 100 }{10}\) = 10
Thus sampling interval = 10 denotes that for every 10 samples one sample

(ii) The first sample is selected from the first 10(sampling interval) samples through selection procedures.

(iii) If the selected first random sample is 5, then the rest of the samples are automatically selected by incriminating the value of the sampling interval 9k = 10. i.e, 5, 15, 25, 35, 45, 55, 65, 75, 85, 95.

Question 10.
Explain in detail about sampling error.
Solution:
Sampling Errors: Errors, which arise in the normal course of investigation or enumeration on account of chance, are called sampling errors. Sampling errors are inherent in the method of sampling. They may arise accidentally without any bias or prejudice.

Sampling Errors arise primarily due to the following reasons:

• Faulty selection of the sample instead of the correct sample by defective sampling technique.
• The investigator substitutes a convenient sample if the original sample is not available while investigating.
• In area surveys, while dealing with borderlines it depends upon the investigator whether to include them in the sample or not. This is known as the Faulty demarcation of sampling units.

Question 11.
Explain in detail the non-sampling error.
Solution:
Non-sampling Errors:
The errors that arise due to human factors which always vary from one investigator to another in selecting, estimating, or using measuring instruments (tape, scale) are called Non-sampling errors. It may arise in the following ways:

• Due to negligence and carelessness on the part of either investigator or respondents
• Due to a lack of trained and qualified investigators.
• Due to the framing of the wrong questionnaire.
• Due to applying the wrong statistical measure.
• Due to incomplete investigation and sample survey.

Question 12.
State any two merits of simple random sampling.
Solution:
Merits:

• In simple random sampling personal bias is completely eliminated.
• This method is economical as it saves time, money and labour.

Question 13.
State any three merits of stratified random sampling.
Solution:
Merits:
(a) A random stratified sample is superior to a sample random sample because it ensures representation of all groups and thus it is more representative of the population which is being sampled.
(b) A stratified random sample can be kept small in size without losing its accuracy
(c) it is easy to administer, if the population under study is sub divided
(d) It reduces the time and expenses in dividing the strata into geographical divisions, since the government itself had the geographical areas.

Question 14.
State any two demerits of systematic random sampling.
Solution:
Demerits:
1. Systematic samples are not random samples.
2. If N is not multiple of n-then the sampling interval (k) cannot be an integer, thus sample selection becomes difficult.

Question 15.
State any two merits for systematic random sampling.
Solution:
Merits of systematic sampling are given below:

• This method distributes the sample more evenly over the entire listed population.
• The time and work are reduced much.

Question 16.
Using the following Tippet’s random number table

Draw a sample of 10 three-digit numbers which are even numbers.
Solution:
There are many ways to select 10 random samples from the given Tippets random number table since the population size is three-digit numbers, Here the door numbers must be even (ie) the unit digit must be even. Here we consider the column-wise selection of random numbers starting from the first column.

So the first sample is 416 and the other 9 samples are 056, 664, 952, 748, 524, 914, 154, 340, and 140.
Tippets random number Table

Question 17.
A wholesaler in apples claims that only 4% of the apples supplied by him are defective. A random sample of 600 apples contained 36 defective apples. Calculate the standard error concerning good apples.
Solution:
sample size = 600; Number of success = 600 – 36 = 564
sample proportion p = \(\frac { 564 }{600}\) = 0.94
600
population proportion (p) = probability of getting good apple = 96%
= \(\frac { 96 }{100}\) {∵ 4% of the apples 100 are defective}
P = 0.96
Q = 1 – p = 1 – 0.96
Q = 0.04
The S.E for a sample proporation is given by
S.E = \(\sqrt{\frac { PQ }{N}}\) = \(\sqrt{\frac { (0.96)(0.04) }{600}}\)
\(\sqrt{\frac { 0.0384 }{600}}\) = \(\sqrt{0.000064}\)
∴ S.E = 0.008
Hence the standard error foe sample proportion is S.E = 0.008

Question 18.
A sample of 1000 students whose mean weight is 119 lbs (pounds) from a school in Tamil Nadu State was taken and their average weight was found to be 120 lbs with a standard deviation of 30 lbs. Calculate standard error of mean.
Solution:
Given n = 1000; \(\bar{x}\) = 119 lbs (pounds)
s = 30 lbs is known in this problem.
since σ is unknown, so we consider \(\bar{σ}\) = s and µ = 120 lbs
S.E = \(\frac { \bar{σ} }{√n}\) = \(\frac { s }{√n}\) = \(\frac { 30 }{\sqrt{1000}}\)
= \(\frac { 30 }{31.623}\) = 0.9487
Therefore the standard error for the average weight of large group of students of 120 lbs is 0.9487

Question 19.
A random sample of 60 observations was drawn from a large population and its standard deviation was found to be 2.5. Calculate the suitable standard error that this sample is taken from a population with standard deviation 3?
Solution:
Sample size n = 60
Sample S.D S = 2.5
population S.D a = 3
The standard error for sample S.D is given by
\(\sqrt{\frac { σ^2 }{2n}}\) = \(\sqrt{\frac { (3)^2 }{2(60)}}\) = \(\frac { 3 }{\sqrt{120}}\)
= \(\frac { 3 }{10.954}\) = 0.27387
= 0.2739
Thus standard error for sample S.D = 0.2739

Question 20.
In a sample of 400 population from a village 230 are found to be eaters of vegetarian items and the rest non-vegetarian items. Compute the standard error assuming that both vegetarian and non-vegetarian foods are equally popular in that village?
Solution:
sample size n = 400
case (i):
sample proporation of vegetarian p = \(\frac { 3 }{10.954}\) = \(\frac { 230 }{400}\)
p = 0.575
q = 1 – p
= 1 – 0.575
q = 0.425
Sample error S.E= \(\sqrt{\frac { pq }{n}}\)
= \(\sqrt{\frac { 0.575×0.425 }{400}}\) = \(\sqrt{\frac { 0.223125 }{400}}\)
\(\sqrt{0.0005578125}\)
S.E = 0.2361

Case(ii):
sample size n = 400
since both vegetarian and non- vegetarian foods are equally popular in that village
sample proparation of vegetarian p = \(\frac { 1 }{2}\) = 0.5
q = 1 -p ⇒ q = 1 – 0.5
q = 0.5

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Accountancy Guide Pdf Chapter 5 Trial Balance Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Accountancy Solutions Chapter 5 Trial Balance

11th Accountancy Guide Trial Balance Text Book Back Questions and Answers

I. Multiple Choice Questions

Choose the correct answer.

Question 1.
Trial balance is a _______.
a) Statement
b) Account
c) Ledger
d) Journal
Answer:
a) Statement

Question 2.
After the preparation of ledger, the next step is the preparation of _______.
a) Trading account
b) Trial balance
c) Journal
d) Profit and loss account
Answer:
b) Trial balance

Question 3.
The trial balance contains the balances of _______.
a) Only personal accounts
b) Only real accounts
c) Only nominal accounts
d) All accounts
Answer:
d) All accounts

Question 4.
Which of the following is/are the objective(s) of preparing trial balance?
a) Serving as the summary of all the ledger accounts
b) Helping in the preparation of final accounts
c) Examining arithmetical accuracy of accounts
d) a, b and c
Answer:
d) a, b and c

Question 5.
While preparing the trial balance, the accountant finds that the total of the1 credit column is short by Rs. 200. This difference will be _______.
a) Debited to suspense account
b) Credited to suspense account
c) Adjusted to any of the debit balance
d) Adjusted to any of the credit balance
Answer:
b) Credited to suspense account

Question 6.
A list which contains balances of accounts to know whether the debit and credit balances are matched is _______.
a) Journal
b) Day book
c) Trial balance
d) Balance sheet
Answer:
c) Trial balance

Question 7.
Which of the following method(s) can be used for preparing trial balance?
a) Balance method
b) Total method
c) Total and Balance method
d) a, b and c
Answer:
d) a, b and c

Question 8.
The account which has a debit balance and is shown in the debit column of the trial balance is _______.
a) Sundry creditors account
b) Bills payable account
c) Drawings account
d) Capital account
Answer:
c) Drawings account

Question 9.
The difference of totals of both debit and credit side of trial balance is transferred to:
a) Trading account
b) Difference account
c) Suspense account
d) Miscellaneous account
Answer:
c) Suspense account

Question 10.
Trial balance is prepared:
a) At the end of the year
b) On a particular date
c) For a year
d) None of the above
Answer:
b) On a particular date

II. Very Short Answer Type Questions

Question 1.
What is a trial balance?
Answer:
A trial balance is a statement containing the debit and credit balances of all ledger accounts on a particular date. It is arranged in the form of debit and credit columns placed side by side and prepared with the object of checking the arithmetical accuracy of entries made in the books of accounts and to facilitate the preparation of financial statements.

Question 2.
Give the format of trial balance.
Answer:
Trial balance is prepared in the following format under the balance method:

Question 3.
What are the methods of preparation of trial balance?
Answer:
Trial Balance is prepared in the following methods:
Balance method: In this method, the balance of every ledger account either debit or credit, as the case may be, is recorded in the trial balance against the respective accounts. The balance method is widely used, as it helps in the preparation of financial statements.

Total method: Under this method, the total amounts on the debit side of the ledger accounts and the total amounts on the credit side of the ledger accounts are ascertained and recorded in the trial balance. This method is not commonly used as it cannot help in the preparation of financial statements.

Total and Balance method: This method is a combination of both the total method and the balance method. Under this method, four columns are provided, namely,

• Totals of the debit side of the ledger accounts,
• Totals of the credit side of the ledger accounts
• Debit balances of ledger accounts and
• Credit balances of the ledger accounts. This method is not in practice.

Question 4.
State whether the balance of the following accounts should be placed in the debit or the credit column of the trial balance:
(i) Carriage outwards
(ii) Carriage inwards
(iii) Sales
(iv) Purchases
(v) Bad debts
(vi) Interest paid
(vii) Interest received
(viii) Discount received
(ix) Capital
(x) Drawings
(xi) Sales returns
(xii) Purchase returns
Answer:

III. Short Answer Questions

Question 1.
What are the objectives of preparing a trial balance?
Answer:
The trial balance is prepared with the following objectives:
1. Test of arithmetical accuracy:
Trial balance is the means by which the arithmetical accuracy of the book-keeping work is checked. When the totals of the debit column and credit column in the trial balance are equal, it is assumed that posting from subsidiary books, balancing of ledger accounts, etc. are arithmetically correct. However, there may be some errors that are not disclosed by the trial balance.

2. Basis for preparing final accounts:
Financial statements, namely, trading and profit and loss account and balance sheet are prepared on the basis of a summary of ledger balances obtained from the trial balance.

3. Location of errors:
When the trial balance does not tally, it is an indication that certain errors have occurred. The errors may have occurred at one or more of the stages of the accounting process, namely, journalizing or recording in subsidiary books, totaling subsidiary books, posting in ledger accounts.

Balancing the ledger accounts, carrying ledger account balances to the trial balance and totaling the trial balance columns, etc. Hence, the errors should be located and rectified before preparing the financial statements.

4. Summarised information of ledger accounts:
The summary of ledger accounts is shown in the trial balance. Ledger accounts have to be seen only when details are required in respect of an account.

Question 2.
What are the limitations of trial balance?
Answer:
The following are the limitations of trial balance:

1. It is possible to prepare a trial balance of an organization, only if the double-entry system is followed.
2. Even if some transactions are omitted, the trial balance will tally.
3. The trial balance may tally even though errors are committed in the books of account.
4. If the trial balance is not prepared in a systematic way, the final accounts prepared on the basis of trial balance may not depict the actual state of affairs of the concern.
5. Agreement of trial balance is not conclusive proof of arithmetical accuracy of entries made

Question 3.
‘A trial balance is only a prima facie evidence of the arithmetical accuracy of records’. Do you agree with this statement? Give reasons.
Answer:
Yes, I agree with the statement. ‘A trial balance is only a prima facie evidence of the arithmetical accuracy of records.
Reasons:
Trial balance is the means by which the arithmetical accuracy of the book – keeping. work is checked. When the totals of the debit column and credit column in the trial balance are equal, it is assumed that porting from subsidiary books, balancing of ledger accounts, etc.

IV. Exercises 

Question 1.
Prepare a trial balance with the following information:

Solution:
Trial Balance:

Question 2.
Prepare the trial balance from the following information:

Solution:
Trial Balance:

Question 3.
Prepare the trial balance from the following balances of Chandramohan as on 31^st March, 2017.

Solution:
In the books of Chandramohan Trial balance as on 31^st March 2017

Question 4.
Prepare the trial balance from the following balances of Babu as on 31^st March, 2016.

Solution:
In The Books of Arjun Trial Balance As On 31^st March 2018

Question 5.
From the following balances of Arjun, prepare the trial balance as on 31^st March, 2018.

Solution:
In The Books of Arjun Trial Balance As On 31^st March 2018

Question 6.
Prepare the trial balance from the following balances of Rajesh as on 31^st March, 2017.

Solution:
In The Books of Rajesh Trial Balance as on 31^st March 2017

Question 7.
Prepare the trial balance from the following balances of Karthik as on 31^st March, 2017.

Solution:
In the books of Karthik Trial Balance as on 31^st March 2018

Question 8.
From the following balances of Rohini, prepare the trial balance as on 31^st March, 2016.

Solution:
In the books of Rohini Trial Balance as on 31^st March 2018

Question 9.
Balan who has a car driving school gives you the following ledger balances. Prepare trial balance as on 31^st December, 2016.

Solution:
In the books of Balan Trial Balance as on 31^st December 2016.

Question 10.
The following balances are extracted from the books of Ravichandran on 31^st December, 2016.

Solution:
In the books of Ravichandran Trial Balance as on 31^st December 2016

Question 11.
From the following balances, prepare trial balance of Baskar as on 31^st March, 2017. Transfer the difference, if any, to suspense account.

Solution:
In the books of Baskar Trial Balance as on 31^st March 2017

Question 12.
From the following balances extracted from the books of Rajeshwari as on 31^st March, 2017, prepare the trial balance.

Solution:
In the books of Baskar Trial Balance as on 31^st March 2017

Question 13.
Correct the following trial balance.

Solution:
Trial Balance:

11th Accountancy Guide Trial Balance Additional Important Questions and Answers

I. Choose the correct answer.

Question 1.
Trial Balance shows arithmetical accuracy of ledger accounts, but it is not a _______ of accuracy.
a) Conclusive
b) Exclusive
c) Submissive
d) Inclusive
Answer:
a) Conclusive

Question 2.
The statement showing balance of all the ledger accounts is known as _______.
a) Trial balance
b) Balance sheet
c) Bank reconciliation statement
d) Profit and loss account
Answer:
a) Trial balance

Question 3.
Which of the following in Trial Balance is contradictory to each other?
a) Inventory and Drawings
b) Sales and Purchases returns
c) Carriage inwards and outward
d) Trade receivable and Liability
Answer:
d) Trade receivable and Liability

Question 4.
Closing stock in the Trial Balance implies that _______.
a) It is already adjusted in the opening stock
b) It is adjusted in sales account
c) It is adjusted in the purchases account
d) None of these
Answer:
c) It is adjusted in the purchases account

Question 5.
The preparation of trial balance is for _______.
a) Locating errors of commission
b) Locating errors of principle
c) Locating clerical errors
d) All of the above
Answer:
d) All of the above

Question 6.
_______ Us Hie most popular method of preparing trial balance.
a) Balance Method
b) Net Asset Method
c) Average Trial Balance method
d) None of the above
Answer:
a) Balance Method

Question 7.
When adjusted purchase is shown on the debit column of the trial balance then
a) Both opening and closing stock do not appear in the trial balance
b) Closing stock is shown in the trial balance and not the opening stock
c) Opening stock is shown in the trial balance and not the closing stock
d) Both opening and closing stock appear in the trial balance
Answer:
b) Closing stock is shown in the trial balance and not the opening stock

Question 8.
A suspense account facilitates the preparation of financial statements even when the has not tallied.
a) Cash Book
b) Ledger
c) Trial Balance
d) Journal
Answer:
c) Trial Balance

Question 9.
Trial Balance is a statement which shows _______ of all accounts.
a) Debit or Credit Balances
b) Balances and Totals
c) Positive and Negative Balances
d) Opening and Closing balances
Answer:
a) Debit or Credit Balances

Question 10.
All the following statements are correct except _______.
a) Trial balance is a statement and not an account
b) Trial balance is prepared at the end of the year
c) Trial balance is not a concluding proof of arithmetical accuracy
d) Trial balance is tallied if a transaction posted twice in the ledger
Answer:
c) Trial balance is not a concluding proof of arithmetical accuracy

Question 11.
Trial balance of a trader shows the following balances: Opening Inventory Rs.9600;Purchases less returns Rs.11850; Salaries Rs.3200;Wages Rs.750; Commission on purchases Rs.200; Carriage outwards Rs.300; Sales Rs.24900; Closing Inventory Rs.3500; Carriage on purchases Rs.1000; Gross profit will be .
a) Rs. 5,000
b) Rs. 6,500
c) Rs. 3,250
d) Rs. 3,200
Answer:
a) Rs. 5,000

Question 12.
Trial Balance is a _______.
a) Real account
b) Nominal account
c) Personal account
d) Statement
Answer:
d) Statement

Question 13.
Bank account will show _______ balance.
a) Debit
b) Credit
c) Debit (or) Credit
d) None
Answer:
a) Debit

Question 14.
Which of the following will affect the agreement of a trial balance?
a) Complete omission of a transaction
b) Partial omission of a transaction
c) Error of principle
d) Compensating errors
Answer:
b) Partial omission of a transaction

Question 15.
Trial balance is prepared to find out the _______.
a) Profit
b) loss
c) financial position
d) Arithmetical accuracy of the accounts
Answer:
d) Arithmetical accuracy of the accounts

Question 16.
Suspense account in the trial balance is entered in the
a) Trading A/c
b) Profit and loss A/c
c) Balance sheet.
d) None of the above
Answer:
c) Balance sheet.

Question 17.
Suspense account having credit balance will be shown on the _______.
a) Credit side of the profit and loss A/c
b) Liabilities side of the balance sheet
c) Assets side of the balance sheet
d) Debit side of the profit and loss A/c
Answer:
b) Liabilities side of the balance sheet

Question 18.
Suspense account having debit balance will be shown on the _______.
a) Credit side of the profit and loss A/c
b) Liabilities side of the balance sheet
c) Assets side of the balance sheet
d) Debit side of the profit and loss A/c
Answer:
c) Assets side of the balance sheet

Question 19.
While preparing the trial balance, the accountant finds that the total of the debit column is short by Rs. 1,000. This difference will be _______.
a) Debited to suspense account
b) Credited to suspense account
c) Adjusted to any of the debit balance
d) Adjusted to any of the credit balance
Answer:
a) Debited to suspense account

Question 20.
The preparation of trial balance is the step in the accounting process.
a) first
b) second
c) third
d) fourth
Answer:
c) third

Question 21.
When double entry system is followed, the totals of the debit and the Credit columns of the trial balance must be _______.
a) Equal
b) unequal
c) Excess
d) Short
Answer:
a) Equal

Question 22.
The account which has a credit balance and is shown in the debit column of the trial balance is
a) Sundry debtors account
b) Bills receivable account
c) Purchases account
d) Capital account
Answer:
d) Capital account

Question 23.
Which one the following represents correct sequence of accounting cycle _______.
a) Journal > Trial balance > Ledger > Transaction
b) Transaction > Journal > Ledger > Trial balance
c) Purchases > Journal > Ledger > Trial balance
d) None of the above
Answer:
b) Transaction > Journal > Ledger > Trial balance

Question 24.
Which one of the following is the most popular method of preparing a trial balance.
a) Total method
b) Balance method
c) Trial and error method
d) Line method
Answer:
b) Balance method

II. Very Short Answer Type Questions

Question 1.
What are the features of Trial Balance?
Answer:

1. Trial balance contains the balances of all ledger accounts.
2. It is prepared on a specific date. That is why, the word, “as on…” is used at the top.
3. When double entry system is followed, the totals of the debit and the credit columns of the trial balance must be equal.
4. If there is a difference between the totals of debit column and credit column of the trial balance, it is an indication of errors being committed somewhere.
5. If both the debit column and the credit column of the trial balance have the same total, it does not mean that there is no mistake in accounting, since some errors are not disclosed by the trial balance.

Question 2.
What are the limitations of trial balance?
Answer:
The following are the limitations of trial balance:

1. It is possible to prepare trial balance of an organisation, only if the double entry system is followed.
   Even if some transactions are omitted, the trial balance will tally.
2. Trial balance may tally even though errors are committed in the books of account.
3. If trial balance is not prepared in a systematic way, the final accounts prepared on the basis of trial balance may not depict the actual state of affairs of the concern.
4. Agreement of trial balance is not a conclusive proof of arithmetical accuracy of entries made in the accounting records.
5. This is because there are certain errors which are not disclosed by trial balance such as complete omission of a transaction, compensating errors and error of principle.

Question 3.
State whether the balance of the following accounts should be placed in the debit or the credit column of the trial balance:
(i) Opening Stock
(ii) Bank Loan
(iii) Provision for Bad debts
(iv) Good will
Answer:

III. Short Answer Questions

Question 1.
What is a Suspense Account?
Answer:
It is used as a place to hold unclassified or disputed funds and expenses. It is used to carry

Question 2.
What are the steps to be followed to prepare trial balance under Balance method?
Answer:
Step 1 : Calculate the balances of all ledger accounts including the cash book.

Step 2 : Record the names of the accounts in the particulars column and the amounts of debit balances in the debit column and credit balances in the credit column.

Step 3 : Enter the page number of ledger from which the balance is taken in the Ledger Folio column.

Step 4 : Total the debit and credit columns. It must be equal. If not equal, locate the errors and make the trial balance agree.

Question 3.
State whether the balance of each of the following accounts should be placed in
The debit or the credit column of the trial balance:
(1) Sundry debtors
(2) Sundry creditors
(3) Cash in hand
(4) Bank overdraft
(5) Salary
(6) Discount allowed
(7) Plant and machinery
(8) Furniture
(9) Commission earned
(10) Reserve Fund
Solution:

Question 4.
What are the advantages of a Trial Balance?
Answer:

1. It helps to ascertain the arithmetical accuracy of the book-keeping work done during the period.
2. It supplies in one place ready reference of all the balances of the ledger accounts.
3. If any error is found out by preparing a trial balance, the same can be rectified before preparing final accounts.
4. It is the basis on which final accounts are prepared.

Specimen of Trial Balance
Trial balance of Mr. X as on –

Question 5.
Prepare Trial Balance with the following information’s:

Solution:
Trial Balance

IV. Exercises

Question 1.
From the following list of balances, prepare a trial balance as on 31.3.2017.

Solution:
Trial Balance as on 31.3.2017

Question 2.
Prepare tare trial balance from the following:

Solution:
Trial Balance

Question 3.
From the following details prepare Trial Balance:

Solution:
Trial Balance

Question 4.
The following are the balances extracted from the books of Mr.M as on 31st December, 2017. Prepare Trial Balance. ,

Solution:
Trial Balance of Mr.M as on 31.12.2017

Question 5.
The following balances were extracted from the ledger of Shri Prasad on 31st March 2017. You are required to prepare a trial balance as on that date in proper form.
Solution:

Trial Balance of Shri Prasad as on 31.3.2017

Question 6.
Prepare Trail Balance.

Solution:
Trail Balance

Question 7.
Redraw correctly the trial balance given below:

Solution:
Corrected Trial Balance

Question 8.
From the following list of balances, prepare Trial Balance:

Solution:
Trial Balance

Question 9.
State whether the balances of the following accounts should be placed in debit column or credit column of the trial balance.

Solution:

Question 10.
From the under mentioned balances extracted from the books of a sole trader on 31st December. Prepare a Trial Balance as on 31st December, 2017.

Solution:

Question 11.
Prepare trial balance as on 31.12.2000 From the followings balances of Mr. Kishore Kumar

Solution:
In the book of Mr. Kishore Kumar Trial balance as on 31^st December 2000

Question 12.
The following balances are extracted from the books of Mr. Anbu. Prepare trial balance as on 30.6.2004.
Solution:
In the book of Mr. Anbu trial balance as on 30.06.2004

Question 13.
Prepare Trial Balance as on 31.3.2004 From the books of Mr. Praveen

Solution:
Prepare Trail Balance as 31.03.2004 from the books Mr. Praveen

Question 14.
Prepare trial balance as on 31.12.2002. From the followings balance of Mr. Ram Prasanth.

Solution:
In the books of Mr. Ram Prasanth trial balance as on 31.12.2002

Question 15.
From the extracats of Mr.Keerthivasan books of accounts prepare Trail balance as on 31.03.94.

In the books of Mr. Keerthivasan trial balance as on 31.03.1994

Question 16.
The Following details have been extracted from Mr. Kirubakaran books of accounts as on 31.12.98.

Solution:
In the books of Mr. Kirubakaran trial balance as on 31.12.1998

Tamilnadu State Board New Syllabus Samacheer Kalvi 12th Business Maths Guide Pdf Chapter 7 Probability Distributions Miscellaneous Problems Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 12th Business Maths Solutions Chapter 7 Probability Distributions Miscellaneous Problems

Question 1.
A manufacturer of metal pistons finds that on the average, 12% of his pistons are rejected because they are either oversize or undersize. What is the probability that a batch of 10 pistons will contain
(a) no more than 2 rejects?
(b) at least 2 rejects?
Solution:
In a binomial distribution
n = 10; p = \(\frac { 12 }{100}\) = \(\frac { 3 }{25}\); q = 1 – p = 1 – \(\frac { 3 }{25}\); q = \(\frac { 22 }{25}\)
p(X = x) = nc_xp^xq^n-x
(a)p(no more than 2 rejects)
p(x ≤ 2) = p(x = 0) + p(x = 1) + p(x = 2)

(b) p (at least 2 rejects) = p (x ≥ 2)

Question 2.
Hospital records show that of patients suffering from a certain disease 75% die of it. What is the probability that of 6 randomly selected patients, 4 will recover?
Solution:
Let x be the random variable of patience suffering from a certain disease
In a binomial distribution
p (X = x) = nc_xp^xq^n-x

Question 3.
If electricity power failures occur according to a Poisson distribution with an average of 3 failures every twenty weeks, calculate the probability that there will not be more than one failure during a particular week.
Solution:
In a poisson distribution
mean(λ) = \(\frac { 3 }{20}\) = 0.15
p(X = x) = \(\frac { e^{-λ}λ^x }{x!}\)
p(not be more than one failure) = p(x ≤ 1)
p(x = 0) + p(x = 1)

= 0.86074 × (1.15)
= 0.98981

Question 4.
Vehicles pass through a junction on a busy road at an average rate of 300 per hour.
1. Find the probability that none passes in a given minute.
2. What is the expected number passing in two minutes?
Solution:
In a poisson distribution
Average per hour = 300 vehicles
mean per minute = \(\frac { 300 }{60}\) = 5
∴ λ = 5

= e^-5(12.5)
= 0.0067379 × 12.5
= 0.08422375
= 0.08422375 × 10²

Question 5.
Entry to a certain University is determined by a national test. The scores on this test are normally distributed with a mean of 500 and a standard deviation of 100. Raghul wants to be admitted to this university and he knows that he must score better than at least 70% of the students who took the test. Raghul takes the test and scores 585. Will he be admitted to this university?
Solution:
Let x denotes the scores of a national test mean
µ = 500 and standard deviation σ = 100
standard normal variate z = \(\frac { x-µ }{σ}\) = \(\frac { x-5000 }{100}\)
when x = 585
z = \(\frac { 585-500 }{100}\) = \(\frac { 85 }{100}\) = 0.85
p(x ≤ 585) = p(z ≤ 0.85)
p(z ≤ 0.85) = p(-∞ < z < 0) + p(0 < z < 0.85)
= 0.5 + 0.3023
= 0.8023
for n = 100;
p(z ≤ 0.85) = 100 × 0.8023
= 80.23
∴ Raehul scores 80.23%

We can determine the scores of 70% of the students as follows:
from the table for the area 0.35
We get z₁ = -1.4(as z₁ lies to left of z = 0)
similarly z₂ = 1.4

Now z₁ = \(\frac { x_1-500 }{100}\) ⇒ -1.4 = \(\frac { x_1-500 }{100}\)
-1.4 × 100 = x₁ – 500 ⇒ x₁ 500 – 140
x₁ = 360
Again z₂ = \(\frac { x_2-500 }{100}\) ⇒ -1.4 = \(\frac { x_1-500 }{100}\)
1.4 × 100 = x₂ – 500 ⇒ x₂ = 140 + 500
= x₂ = 640
Hence 70% of students score between 360 and 640
But Raghul scored 585. His score is not better than the score of 70% of the students.
∴ He will not be admitted to the university.

Question 6.
The time taken to assemble a car in a certain plant is a random variable having a normal distribution of 20 hours and a standard deviation of 2 hours. What is the probability that a car can be assembled at this plant in a period of time.
(i) less than 19.5 hours?
(ii) between 20 and 22 hours?
Solution:
Let x denotes the time taken to assemable cars mean µ = 20 hours and S.D σ = 2 hours
The standard normal variate
z = \(\frac { x-µ }{σ}\) = \(\frac { x-20 }{2}\)
(i) p(less than 19.5 hours) = p(x < 19.5)
when x = 19.5
z = \(\frac { 19.5 }{2}\) = \(\frac { -0.5 }{2}\) = 0.25
p(x < 19.5) = p(z < – 0.25)
= p(-∞ < z < 0) – p(-0.25 < z < 0)
= 0.5 – p(0 < z < 0.25)
= 0.5 – 0.0987
= 0.4013

(ii) p(between 20 and 22 hours) = p(20 < x < 22)

when x = 20
z = \(\frac { 20-20 }{2}\) = \(\frac { 0 }{2}\) = 0
when x = 22;
z = \(\frac { 22-20 }{2}\) = \(\frac { 2 }{2}\) = 1
p(20 < x < 22) = p(0 < z < 1)
= 0.3413

Question 7.
The annual salaries of employees in a large company are approximately normally distributed with a mean of $50,000 and a standard deviation of $20,000.
(a) What percent of people earn less than $40,000?
(b) What percent of people earn between $45,000 and $65,000?
(c) What percent of people earn more than $75,000
Solution:
Let x denotes the annual salaries of employees in a large company
mean µ = 50,000 and S.D σ = 20,000
Standard normal variate z = \(\frac { x-µ }{σ}\)
(a) p(people earn less than $40,000) = p(x < 40,000)
when x = 40,000
z = \(\frac { 40,000-50,000 }{20,000}\) = \(\frac { 10,000 }{20,000}\)
z = -0.5
p(x < 40,000) = p(z < -0.5)
= p(-∞ < z < 0) – p(-0.5 < z < 0)
= 0.5 -p(-0.5 < z <0)
= 0.5 – p(0 < z < 0.5) (due to symmetry)
= 0.5 – 0.01915
= 0.3085
= p(x < 40,000) in percentage = 0.3085 × 100 = 30.85

(b) p(people ear between $45,000 and $65,000)
p(45000 < x < 65000)
When x = 45,000;
z = \(\frac { 45,000-50,000 }{20,000}\) = \(\frac { -5000 }{20,000}\) = \(\frac { -1 }{4}\)
z = -0.25
when x = 65,000;
z = \(\frac { 65,000-50,000 }{20,000}\) = \(\frac { 15000 }{20,000}\) = \(\frac { 3 }{4}\)
z = 0.75
p(45000 < x < 65000) = p(-0.25 < z < 0.75)
= p(-0.25 < z < 0) + p(0 < z < 0.75)
= p(0 < z < 0.25) + p(0 < z < 0.75)
= p(0 < z < 0.25) + p(0 < z < 0.75)
= 0.0987 + 0.2734 = 0.3721
p(45000 < x < 65000) in percentage = 0.3721 × 100
= 37.21

p(people earn more than$75,000) = p(x > 70000)
when x = 75,000;
z = \(\frac { 75,000-50,000 }{20,000}\) = \(\frac { 25000 }{20,000}\) = \(\frac { 5 }{4}\)
z = 1.25
p(x > 75,000) = p(x > 1.25)
= p(0 < z < ∞) – p(0 < z < 1.25) = 0.5 – 0.3944 = 0.1056 p(x > 750,000)in percent = 01056 × 100
= 10.56

Question 8.
X is a normally normally distributed variable with mean µ = 30 and standard deviation σ = 4. Find
(a) P(x < 40) (b) P(x > 21)
(c) P(30 < x < 35)
Solution:
x is a normally distributed variable with mean µ = 30 and standard deviation σ = 4

Then the normal variate z = \(\frac { x-µ }{σ}\) = \(\frac { x-30 }{4}\)

(a) p(x < 40) = ?
when x = 40;
z = \(\frac { 40-30 }{4}\) = \(\frac { 10 }{4}\) = 2.5
p(x < 40) = p(z < 2.5)
= p(-∞ < z < 0) + p(0 < z < 2.5) = 0.5 + 0.4938 = 0.9938 (b) p(x > 21) = ?
when x = 21;
z = \(\frac { 40-30 }{4}\) = \(\frac { 10 }{4}\) = -2.25
p(x > 21) = p(z > -2.25)
= p(-2.25 < z < 0) + p(0 < z < ∞)
= p(0 < z < 2.25) + 0.5
= 0.4878 + 0.5
= 0.9878

(c) p(30 < x < 35) = ?
when x = 30;
z = \(\frac { 30-30 }{4}\) = \(\frac { 0 }{4}\) = 0
when x = 35;
z = \(\frac { 35-30 }{4}\) = \(\frac { 5 }{4}\) = 1.25
p(30 < x < 35) = p(0 < z < 1.25)
= 0.3944

Question 9.
The birth weight of babies is Normally distributed with mean 3,500 g and standard deviation 500 g. What is the probability that a baby is born that weighs less than 3,100 g?
Solution:
Let x be a normally distributed variable with mean 3,500 g and standard deviation 500 g

Here µ = 3500 and σ = 500
The standard normal variate z = \(\frac { x-µ }{σ}\)
p(weight less than variate 3100 g) = p(x < 3100)
when x = 3100;
z = \(\frac { 3100-3500 }{500}\) = \(\frac { -400 }{500}\) = \(\frac { -4 }{5}\)
z = -0.8
∴ p(z < 3100) = p(z < -0.8)
= p(-∞ < z < 0) – p(-0.8 < z < 0)
= 0.5 – p(0 < z < 0.8)
= 0.5 – 0.2881
= 0.2119

Question 10.
People’s monthly electric bills in chennai are normally distributed with a mean of Rs 225 and a standard deviation of Rs 55. Those people spend a lot of time online. In a group of 500 customers, how many would we expect to have a bill that is Rs 100 or less?
Solution:
Let X be a normally distributed variable with a mean of Rs 225 and a standard deviation of Rs 55

Given mean µ = 225 and s.d σ = 55
Now the probability that the bill will be ₹100 or less is P (X ≤ 100)
= P(Z ≤ \(\frac{100-225}{55}\))
= P(Z ≤ -2.27)
= 0.5 – P(-2.27 < Z < 0)
= 0.5 – P(0 < Z < 2.27)
= 0.5 – 0.4884
= 0.0116
Thus, in a group of 500 customers, we expect to have 500 × 0.0116 = 5.8 ~ 6 customers whose electric bills will be ₹ 100 or less.

Tamilnadu State Board New Syllabus Samacheer Kalvi 12th Business Maths Guide Pdf Chapter 7 Probability Distributions Ex 7.3 Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 12th Business Maths Solutions Chapter 7 Probability Distributions Ex 7.3

Question 1.
Define normal distribution.
Solution:
A random variable X is said to follow a normal distribution with parameters mean µ and varaince σ², if its probability density function is given by

Question 2.
Define standard normal variate.
Solution:
A random variable Z = (X – µ)/σ follows the standard normal distribution. Z is called the standard normal variate with mean 0 and standard deviation 1 i.e Z – N (0, 1). Its Probability density function is given by:
φ(z) = \(\frac { 1 }{\sqrt {2π}}\) e^-x²/2 -∞ < z < ∞

Question 3.
Write down the conditions in which the normal distribution is a limiting case of the binomial distribution.
Solution:
The Normal distribution is a limiting case of Binomial distribution under the following conditions:

• n, the number of trials is infinitely large, i.e. n → ∞
• neither p (or q ) is very small.

Question 4. m
Write down any five characteristics of the normal probability curve.
Solution:
Chief Characteristics or Properties of Normal Probability distribution and Normal probability Curve.
The normal probability curve with mean µ and standard deviation σ has the following properties:
(i) the curve is bell-shaped and symmetrical about the line x = u.
(ii) Mean, median, and mode of the distribution coincide.
(iii) x-axis is an asymptote to the curve, (tails of the curve never touches the horizontal (x) axis)
(iv) No portion of the curve lies below the x-axis as f(x) being the probability function can never be negative.
(v) The points of inflexion of the curve are x = µ ± σ

Question 5.
In a test on 2,000 electric bulbs, it was found that bulbs of a particular make, was normally distributed with an average life of 2,040 hours and a standard deviation of 60 hours. Estimate the number of bulbs likely to burn for
(i) more than 2,150 hours
(ii) less than 1,950 hours
(iii) more 1,920 hours but less than 2,100 hours.
Solution:
Let x denote the burning of the bulb follows normal distribution with mean 2,040 and standard deviation 60 hours.
Here m = 2040; σ = 60 and N = 2000
The standard normal variate
z = \(\frac { x-µ }{σ}\) = \(\frac { x-2040 }{60}\)
(i) p(morethan 2,150 hours)
p(x > 2150)
when x = 2150
z = \(\frac { 2150-2040 }{60}\) = \(\frac { 110 }{60}\)= 1.833
p(x > 2150) = p(z > 1.833)
= p(0 < z < ∞) – p(0 < z < 1.833)
= 0.5 – 0.4664
= 0.0336
∴ Number of bulbs whose burning time is more than 2150 hours=0.0336 × 2000
= 67.2 = 67(approximately)

(ii) p(less than 1950 hours)
p(x < 1950)
when x = 1950
z = \(\frac { 1950-3040 }{60}\) = \(\frac { -90 }{60}\)= -1.5
p(x < 1950) = p(z < -1.5) = p(z > 1.5)
= 0.5 – 0.4332
= 0.068

Numbers of bulbs whose burning time is less than
1950 = 0.0668 × 2000 = 133.6
= 134 (approximately)

(iii) p(more 1,920 hours but less than 2,100 hours)
= p(1920 < x < 2100)
when x = 1950
z = \(\frac { 1920-2040 }{60}\) = \(\frac { -120 }{60}\)= -2
when x = 2100
z = \(\frac { 2100-2040 }{60}\) = \(\frac { -60 }{60}\)= -2
∴ p(1920 < x < 2040) = p(-2 < z < 1)
= p(0 < z < 2) + p(0 < z < 1)
= 0.4772 + 0.3413
= 0.8185

∴ Number of bulbs whose burning time more than 1920 hours but less than 2100 hours) = 0.8185 × 2000
= 1637

Question 6.
In a distribution, 30% of the items are under 50 and 10% are over 86. Find the mean and standard deviation of the distribution.
Solution:

z = \(\frac { x-µ }{σ}\)
Given that
p(x < 50) = 0.3 p(x > 86) = 0.1
p(z < -c) = 0.3
p(-c < z < 0) = 0.5 – 0.3
p(-c < z < 0) = 0.2 {from the table}
p(0 < z < c) = 0.2
c = 0.53
then -c = -0.53
∴ \(\frac { 50-µ }{σ}\) = -0.53
50 – µ = -0.53σ
µ – 0.53σ = 50 → 1
p(x < 50) = 0.1
p(0 < z < ∞) = -p(0 < z < c₁) = 0.1
p(0 < z < ∞) = p(0 < z < c₁) + 0.1
0.5 = p(0 < z < c₁) + 0.1
p(0 < z < c₁) = 0.5 – 0.1
p = (0 < z < c₁) = 0.4
c₁ = 1.29
∴ \(\frac { 86-µ }{σ}\) = 1.29
86 – µ = 1.29 σ
µ + 1.29σ = 86 → 2
solving eqn 1 & 2
eqn 2 ⇒ m + 1.29σ = 86
eqn 1 ⇒ m + 0.53σ = 50
– + – ………….
………… 1.82 ………… σ = 36 ………….
σ = \(\frac { 36 }{1.82}\) ∴ = 19.78
Substitute σ = 19.78 in eqn 1
µ – 0.53(19.78) = 50
µ -10.48 = 50
µ = 50 + 10.48
µ = 60.48
Mean = 60.48 and standard deviation = 19.78

Question 7.
X is normally distributed with mean 12 and sd 4. Find P (x ≤) 20 and P (0 ≤ x ≤ 12)
Solution:
x is normally distribution with mean 12 and sd 4
∴ µ = 12 and σ = 4
Standard normal variable
z = \(\frac { x-µ }{σ}\) = \(\frac { x-12 }{4}\)
(i) p(x ≤ 20)

when x = 20
z = \(\frac { 20-12 }{4}\) = \(\frac { 8 }{4}\) = 2
v(x ≤ 20) = \(\frac { 8 }{4}\) = 2
p(x ≤ 20) = p(z ≤ 2)
= 0.5 + p(0 < z < 2)
= 0.5 + 0.4772
= 0.9772

(ii) p(0 < x < 12 )

when x = 0
z = \(\frac { 0-12 }{4}\) = \(\frac { -12 }{4}\) = -3
when x = 12
z = \(\frac { 12-12 }{4}\) = \(\frac { 0 }{4}\) = 0
p(0 ≤ x ≤ 12) = p(-3 ≤ z ≤ 0)
= p(0 ≤ z ≤ 3)
= 0.4987

Question 8.
If the heights of 500 students are normally distributed with mean 68.0 inches and standard deviation 3.0 inches, how many students have height
(a) greater than 2 inches
(b) less than or equal to 64 inches
(c) between 65 and 71 inches.
Solution:
let x denote the height of a student N = 500; m = 68.0 inches and σ = 3.0 inches the standard normal variate
z = \(\frac { x-µ }{σ}\) = \(\frac { x-68 }{3}\)
a(greater than 72 inches)
p = p(x > 72)
when x = 72
z = \(\frac { 72-68 }{3}\) = \(\frac { 4 }{3}\) = 1.33
p(x > 72) = p(z > 1.33)
= 0.5 – 0.4082
= 0.0918

Number of students whose height are greater than 72 inches
= 0.0918 × 500
= 45.9
= 46 (approximately)

(b) p(less than or equal to 64 inches)
p(x ≤ 64)
when x = 64
z = \(\frac { 64-68 }{3}\) = \(\frac { -4 }{3}\) = -1.33
p(x ≤ 64) = p(z ≤ -1.33)
p(z ≥ -1.33)
= 0.5 – 0.4082
= 0.0918

∴ Number of heights whose ate less than or equal to 64 inches = 0.0918 × 500
= 45.9
= 46 (approximately)

(c) p(between 65 and 71 inches)
p(65 ≤ x ≤ 71)
when x = 65

z = \(\frac { 65-68 }{3}\) = \(\frac { -3 }{3}\) = -1
when x = 71
z = \(\frac { 71-68 }{3}\) = \(\frac { 3 }{3}\) = 1
p(65 ≤ x ≤ 71) = p(-1 < z < 1)
= p(-1 < z < 0) + p(0 < z < 1)
= p(0 < z < 1) + p(0 < z < 1)
= 2 × [p(0 < z < 1)]
= 2 × 0.3413
= 0.6826
∴ Number of students whose height between 65 and 7 inches = 0.6826 × 500
= 341.3
= 342 (approximately)

Question 9.
In a photographic process, the developing time of prints may be looked upon as a random variable having the normal distribution with a mean of 16.28 seconds and a standard deviation of 0.12 second. Find the probability that it will take less than 16.35 seconds to develop prints.
Solution:
let x be the random variable have long the normal distribution with a mean of 16.28 seconds and a standard deviation of 0.12 second

µ = 16,28 and σ = 0.12
The standard normal variate
z = \(\frac { x-µ }{σ}\) = \(\frac { x-16.28 }{0.12}\) = 1
p(less than 16.35 seconds) = p(x < 16.35)
when x = 16.35
z = \(\frac { 16.35-16.28 }{0.12}\) = \(\frac { 0.07 }{0.12}\) = 0.583
p(x< 16.35) = p(z < 0.583)
= p(—∞ < z < 0) + p(0 < z < 0.583)
= 0.5 + 0.2190
= 0.7190

Question 10.
If the heights of 500 students are normally distributed with mean of 68.0 inches and standard deviation of 3.0 inches, how many students have a height (a) greater than 2 inches (b) less than or equal to 64 inches (c) between 65 and 71 inches.
Solution:
Let x be a normal variate with mean of 400 labour days and a standard deviation of 100 labour days
m = 400 and σ = 100
The construction work should be completed within 450 days.
The standard normal variate
\(\frac { x-µ }{6}\) = \(\frac { x-400 }{100}\)
personality for 1 labour day = Rs 10,000
If personality amount is = 2,00,000 than No of excess

days = \(\frac { 200000 }{10000}\) = 20
∴ x = 450 + 20 = 470
when x = 470
z = \(\frac { 470-400 }{100}\) = \(\frac { 70 }{100}\) = 0.7
= p(x ≥ 470) = p(z ≥ 0.7)
= 0.5 – 0.2580
= 0.2420

(ii) p(at most 500 days) = p(x ≤ 500 )
when x = 500

z = \(\frac { 500-400 }{100}\) = \(\frac { 100 }{100}\) = 1
p(x ≤ 500) = p(z ≤ 1)
= p(∞ < z < 0) -r- p(0 < z < 1)
= 0.5 + 0.3415
= 0.8413

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Bio Zoology Guide Pdf Chapter 10 Neural Control and Coordination Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Bio Zoology Guide Chapter 10 Neural Control and Coordination

11th Bio Zoology Guide Neural Control and Coordination Text Book Back Questions and Answers

Part – I

I. Choose The Best Options

Question 1.
Which structure in the ear converts pressure waves to action potentials?
a) Tympanic membrane
b) Organ of Corti
c) Oval window
d) Semicircular canal
Answer:
b) Organ of Corti

Question 2.
Which of the following pairings is correct
a) Sensory nerve – afferent
b) Motor nerve – afferent
c) Sensory nerve – ventral
d) Motor nerve – dorsal
Answer:
a) Sensory nerve – afferent

Question 3.
During synaptic transmission of nerve impulse, a neurotransmitter (P) is released from synaptic vesicles by the action of ions
(Q). Choose the correct P and Q.
a) P = Acetylcholine, Q = Ca⁺⁺
b) P = Acetylcholine, Q = Na⁺
c) P = GABA, Q = Na⁺
d) P = Cholinesterase, Q = Ca⁺⁺
Answer:
a) P = Acetylcholine, Q = Ca⁺⁺

Question 4.
Examine the diagram of the two cell types A and B given below and select the correct option.
a) Cell – A is the rod cell found evenly all over the retina
b) Cell – A is the cone cell more concentrated in the fovea centralis
c) Cell – B is concerned with colour vision in bright light
d) Cell – A is sensitive to bright light intensities

Answer:
c) Cell – B is concerned with colour vision in bright light

Question 5.
Assertion- The imbalance in the concentration of Na⁺, K^+, and proteins generates an action potential.
Reason: To maintain the unequal distribution of Na⁺ and K⁺, the neurons use electrical energy.
a) Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.
b) Both Assertion and Reason are true but the 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 the Assertion.

Question 6.
Which part of the human brain is concerned with the regulation of body temperature?
a) Cerebellum
b) Cerebrum
c) Medulla oblongata
d) Hypothalamus
Answer:
d) Hypothalamus

Question 7.
The respiratory centre is present in the
a) Medulla oblongata
b) Hypothalamus
c) Cerebellum
d) Thalamus
Answer:
a) Medulla oblongata

Question 8.
Match the following human spinal nerves in column I with their respective number in column II and choose the correct option
Column I Column 11
(P) Cervical nerves
(Q) Thoracic nerve
(R) Lumbar nerve
(S) Coccygeal nerve
(i) 5 pairs
(ii) 1 pair
(iii) 12 pairs
(iv) 8 pairs
a) (P-iv), (Q-iii), (R-i), (S-ii)
b) (P-iii), (Q-i), (R-ii), (S-iv)
c) (P-iv), (Q-i), (R-ii), (S-iii)
d) (P-ii), (Q-iv), (R-i), (S-iii)
Answer:
a) (P-iv), (Q-iii), (R-i), (S-ii)

Question 9.
Which of the following cranial nerve controls the movement of eye ball?
a) Trochlear nerve
b) Optic nerve
c) Olfactory nerve
d) Vagus nerve
Answer:
a) Trochlear nerve

Question 10.
The abundant intracellular cation is
a) H⁺
b) K⁺
c) Na⁺
d) Ca⁺⁺
Answer:
b) K⁺

Question 11.
Which of the following statements is wrong regarding the conduction of nerve impulse.
a) In a resting neuron, the axonal membrane is more permeable to K⁺ ions and nearly impermeable to Na⁺ ions.
b) Fluid outside the axon has a high concentration of Na⁺ ions and a low concentration of K⁺, in a resting neuron.
c) Ionic gradient s are maintained by Na⁺ K⁺ pumps across the resting membrane, which transport 3 Na ions outwards for 2K⁺ into the cell.
d) A neuron is polarized only when the outer surface of the axonal membrane possess a negative charge and its inner surface is positively charged.
Answer:
b) Fluid outside the axon has a high concentration of Na⁺ ions and a low concentration of K⁺, in a resting neuron.

Question 12.
All of the following are associated with the myeline sheath except
a) Faster conduction of nerve impulses
b) Nodes of Ranvier forming gaps along the axon
c) Increased energy output for nerve impulse conduction
d) Saltatory conduction of action potential
Answer:
c) Increased energy output for nerve impulse conduction

Question 13.
Several statements are given here in reference to cone cells which of the following option indicates all correct statements for cone cells? Statements
(i) Cone cells are less sensitive in bright light than Rod cells
(ii) They are responsible for colour vision
(iii) Erythropsin is a photo pigment which is sensitive to red colour light
(iv) They are present in fovea of retina
a) (iii), (ii) and (i)
b) (ii), (iii) and (iv)
c) (i), (iii) and (iv)
d) (i), (ii) and (iv)
Answer:
c) (i), (iii) and (iv)

Question 14.
Which of the following statement concerning the somatic division of the peripheral neural system is incorrect?
a) Its pathways innervate skeletal muscles
b) Its pathways are usually voluntary
c) Some of its pathways are referred to as reflex arcs
d) Its pathways always involve four neurons
Answer:
d) Its pathways always involve four neurons

Question 15.
When the potential across the axon membrane is more negative than the normal resting potential, the neuron is said to be in a state of
a) Depolarization
b)FIyperpo1ariation
c) Repolarization
d) Hypopolaiization
Answer:
c) Repolarization

Question 16.
Why is the blind spot called so?
Answer:
Slightly below the posterior pole of the eye, the optic nerve and the retinal blood vessels enter the eye. This region is devoid of rods and cones. Hence, this region is called a blind spot.

Question 17.
Sam’s optometrist tells him that his intraocular pressure is high. What is this condition called and which fluid does it involve?
Answer:

• The increase in intraocular pressure leads to the disease called Glaucoma.
• Any block in the canal of Schlemm increases the intraocular pressure of aqueous humor and leads to ‘Glaucoma’ where the optic nerve and the retina are compressed due to pressure.

Question 18.
The action potential occurs in response to a threshold stimulus: but not at sub-threshold stimuli. what is the name of the principle involved?
Answer:
The olfactory nerve carries the sense of smell to the sensory strip present in the cerebrum. The sensory areas are present in the parietal lobe of the cerebrum. The stimuli of smell reaches the mammillary bodies present in the hypothalamus. This produces olfactory reflexes and emotional responses to odour.

Question 19.
Pleasant smell of food urged Ravi to rush into the Kitchen. Name the parts of the brain involved in the identification of food and emotional responses to odour
Answer:
The hypothalamus contains a pair of small rounded body called mamillary bodies that are involved in olfactory reflexes and emotional responses to odour
This is also act as centre for appetite thirst and heat regulation.

Question 20.
Cornea transplant in humans is almost never rejected State the reason.
Answer:
Cornea does not have blood vessels. Hence there is no possibility of rejection when the cornea is transplanted from one person to another person.

Question 21.
At the end of repolarisation, the nerve membrane gets hyperpolarized Why?
Answer:
If repolarization becomes more negative than the resting potential – 70mV to about – 90mV it is called hyperpolarization.

Question 22.
Label the parts of the neuron.
Answer:

A- Nucleus with nucleolus
B- Axolemma
C- Dendrites
D- Myelin sheath, Nucleus
E- Axon (Direction of signal transmission)
F- Node of Ranvier.

Question 23.
The choroid plexus secretes cerebral spinal fluid List the function of it.
Answer:
Cerebrospinal fluid provides buoyancy to the central nervous system.

1. It acts as a shock absorber for the brain and spinal cord.
2. It nourishes the brain cells by transporting food and oxygen.
3. It carries harmful metabolic wastes from the brain to the blood.
4. It maintains constant pressure inside the cranial vessels.

Question 24.
What is the ANS controlling center? Name the parts that are supplied by the ANS?
Answer:
Controlling center – autonomic neural system. Controlling organs.

1. Eyes
2. Salivary Glands
3. Heart
4. Lungs
5. Stomach
6. Liver
7. Kidney
8. Intestines
9. Bladder

Question 25.
Why the limbic system is called the emotional brain. Name the parts of it?
Answer:
The limbic system is a set of components located on both sides of the thalamus present in the inner part of the cerebral hemisphere. It includes the olfactory bulbs, cingulate gyrus, mammillary body, amygdala, hippocampus, and hypothalamus. The limbic system plays a primary role in the regulation of pleasure, pain, anger, fear, sexual feeling, affection, and memory. Hence it is called the emotional brain.

Question 26.
Classify receptors based on the type of stimuli.
Answer:

Receptors	Stimulus	Effector organs
Mechano receptors	Pressure and vibration	Mechano receptors are present in the cochlea of the inner ear and the semicircular canal and utriculus
Chemoreceptors	Chemicals	Taste buds in the tongue and nasal epithelium
Thermo receptors	Temperature	Skin
Photoreceptors	Light	Rod and cone cells of the retina in the eye.

Question 27.
Name the first five cranial nerves, their nature and their functions
Answer:

Cranial nerves	Nature of nerve	Function
I. Olfactory nerve	Sensory	Sense of smell
II.Optic nerves	Sensory	Sense of sight
III. Oculo motor nerves	Motor	Movement of the eye
IV. Trochlear nerve	Motor	Rotation of the eyeball
V.Trigeminal nerve	Sensory and motor mixed	The functioning of face ball

Question 28.
The sense of taste is considered to be the most pleasurable of all senses. Describe the structure of the receptor involved with a diagram.
Answer:

• The sense of taste is considered to be the most pleasurable of all senses.
• The tongue is provided with many small projections called papillae.
• Taste buds are located mainly on the papillae.
• Taste buds are flask-shaped.

There are two major types.

• Gustatory epithelial cells or taste cells.
• Basal epithelial cells or repairing cells.

• Long microvilli called gustatory hairs project from the tip of the gustatory cells and extend through a taste pore to the surface of the epithelium.
• Gustatory hairs are the sensitive portion of the gustatory cells and they have sensory dendrites which send the signal to the brain.
• The basal cells that act as stem cells divide and differentiate into new gustatory cells.

Question 29.
Describe the structures of olfactory receptors?
Answer:
The smell receptors are excited by air-borne chemicals that dissolve in fluids. The yellow coloured patches of olfactory epithelium form the olfactory organs that are located on the roof of the nasal cavity.

The olfactory epithelium is covered by a thin coat of mucus layer below and olfactory glands bounded connective tissues, above. It contains three types of cells: supporting cells, Basal cells and millions of pin-shaped olfactory receptor cells (which are unusual bipolar cells).

The olfactory glands and the supporting cells secrete the mucus. The unmyelinated axons of the olfactory receptor cells are gathered to form the filaments of the olfactory nerve [cranial nerve-I] which synapses with cells of the olfactory bulb.

The impulse, through the olfactory nerves, is transmitted to the frontal lobe of the brain for identification of smell and the limbic system for the emotional responses to odour.

Part-II.

11th Bio Zoology Guide Neural Control and Coordination Additional Important Questions and Answers

I. Choose The Correct Answer

Question 1.
Which of the following acts as a phagocytic cell to engulf the foreign particles at the time of any injury to the brain?
(a) Neuron
(b) Neurilemma
(c) Neuroglia
(d) Axolemma
Answer:
(b) Neurilemma

Question 2.
Name the nutritive cells of neurons.
a) Axon
b) Neuroglia
c) Schwann’s cell
d) Epithelial cells.
Answer:
b) Neuroglia

Question 3.
Which of the following has bipolar neurons?
(a) Intemeurons
(b) Cranial nerves
(c) Spinal nerves
(d) Inner ear
Answer:
(d) Inner ear

Question 4.
Name the plasma membrane which surrounds the neurons?
a) Neurilemma
b) Axolemma
c) Myalin membrane
d) Sarcolemma
Answer:
a) Neurilemma

Question 5.
The interior of the cell of the resting neuron is negative due to ……………….
(a) Greater efflux of Na⁺ outside the cell than, K⁺ influx into the cell.
(b) Only greater efflux of Na⁺ outside the cell.
(c) Greater efflux of K⁺ outside the cell than Na⁺ influx into the cell.
(d) Only greater efflux of K⁺ outside the cell.
Answer:
(c) Greater efflux of K⁺ outside the cell than Na⁺ influx into the cell.

Question 6.
Where are Nissl’s bodies seen in the nerve cell?
a) Cell body and dendrites
b) Cell body and axon
c) Cell body and myelin sheath
d) Cell body and end plate of the axon.
Answer:
a) Cell body and dendrites

Question 7.
When the membrane potential shoots rapidly upto +45 mV, it is called the ………………….
(a) Threshold potential
(b) Spike potential
(c) Repolarization
(d) Hyperpolarization
Answer:
(b) Spike potential

Question 8.
Cell forms the myelin sheath ……………..
a) Schwaan’s cell
b) Neuroglial cells
c) Nephron
d) Epithelial cells
Answer:
a) Schwaan’s cell

Question 9.
The subarachnoid space is present in between ………………..
(a) Piamater and arachnoid mater
(b) Arachnoid mater and duramater
(c) Brain and Piamater
(d) Spinal cord and duramater
Answer:
(a) Piamater and arachnoid mater

Question 10.
Which of the following does the work of phagocytosis of microbes during the infection of the brain
a) Schwann cells
b) Node of Ranvier
c) Neuroglial cells
d) Neurilemma
Answer:
c) Neuroglial cells

Question 11.
Which of the following plays a key role in learning and memory?
(a) Hypothalamus
(b) Pons Varolii
(c) Thalamus
(d) Medulla oblongata
Answer:
(c) Thalamus

Question 12.
Find out the wrong pair
a) Multi polar neuron: One axon and two or more dendrites.
b) Bi polar neurons: One axon and more than two dendrites.
c) Uni polar neurons: Short process axon.
d) Synaptic Knob: Neurotransmitters
Answer:
b) Bi polar neurons: One axon and more than two dendrites.

Question 13.
The reflex action is effected by ……………..
(a) Brain
(b) Medulla oblongata
(c) Effector organs
(d) Spinal cord
Answer:
(d) Spinal cord

Question 14.
Match the following and find the answer.

1. Leakage channels	a. Opens through the sensation of touch and pressure.
2. Ligand-gated channels	b. They are stable.
3. Voltage gated channels	c. Opens through chemical stimulation.
4. Charged particles	d. Ionic channels are always open.

Answer:
c) i- B,ii – D,iii – C,iv – A

Question 15.
Which of the following is produced at the terminal ends of the postganglionic fibres at the effector organs of the parasympathetic neural system?
(a) Noradrenaline
(b) Acetylcholine
(c) Adrenalin
(d) Melatonin
Answer:
(b) Acetylcholine

Question 16.
Where are bipolar neurons situated?
a) Cranial nerves
b) Olfactory lobes of the brain
c) Spinal nerves
d) Skin
Answer:
b) Olfactory lobes of the brain

Question 17.
Which of the following absorbs light to prevent internal reflection in the eye?
(a) Sclera
(b) Retina
(c) Chorid
(d) Cornea
Answer:
(c) Chorid

Question 18.
Find out the odd one.
a) Schwann cell – Myalin sheath
b) Synaptic knob – Synaptic vesicles
c) Bipolar neuron – Cranial nerves
d) Multipolar neuron – Spinal nerves.
Answer:
c) Bipolar neuron – Cranial nerves

Question 19.
The defect hypermetropia can be overcome by using ……………
(a) Concave lens
(b) Convex lens
(c) Cylindrical glass
(d) Surgical procedures
Answer:
(b) Convex lens

Question 20.
Match and find the correct sequence.

I. Neuro junction	a. Neuron which receives a stimulus
II. Presynaptic neurons	b. Synaptic vesicles
III. Synaptic cleft	c. Synapses
IV. Neurotransmitter	d. Pre and post neuron junction

a) I-d II-a II-c IV-d
b) I-a II-c III-d IV-b
c) I-a II-b III-c IV-d
d) I-c II-a III-d IV-b
Answer:
d) I-c II-a III-d IV-b

Question 21.
The olfactory impulses are transmitted to the ……………….. lobe of the brain.
(a) Parietal
(b) Temporal
(c) Occipital
(d) Frontal
Answer:
(d) Frontal

Question 22.
Find out whether the following statements are true or false. Find out the correct sequence.
i. The thick outer covering of the brain is dura matter
ii. The space between pia matter and dura matter is subarachnoid space.
iii. The membrane that surrounds the brain is piamalter
iv. The space between arachnoid and pia mater is subarachnoid space
a) I – False; II – False; III – True; IV – True
b) I-True; II-False; III-True; IV-True
c) I – True; II – False; III – False; IV – True
d) I-True; II-False; III-True; IV-False
Answer:
b) I-True; II-False; III-True; IV-True

Question 23.
Which of the following are present in the fingertips and soles of the feet?
(a) Pacinian corpuscles
(b) Meissner’s corpuscles
(c) Ruffini endings
(d) Krause end bulbs
Answer:
(b) Meissner’s corpuscles

Question 24.
Find out whether the following statements are true or false.
a) At resting membrane potential the efflux of potassium is more than the influx of sodium from the outer surface of the neurilemma.
b) When the stimulus is sent from the cell body to the axon there is no creation of action potential.
c) The spike potential is +45mV.
d) The threshold potential is +55mV.
i) a) True b) True c) False d) False
ii) a) False b) True c) True d) True
iii) a) True b) False c) True d) True
iv) a) True b) False c) True d) False
Answer:
iv) a) True b) False c) True d) False

Question 25.
The protein part of the photopigment is ………………..
(a) Retinal
(b) Opsin
(c) Macula lutea
(d) Fovea centralis
Answer:
(A) Opsin

Question 26.
………………. is the part of the fore-brain.
a) Cerebrum – Mesencephalon
b) Cerebrum – Prosencephalon
c) Cerebrum – Diencephalon
d) Cerebrum – Parietal lobe.
Answer:
c) Cerebrum – Diencephalon

Question 27.
…………………….. is useful in the diagnosis of neurological and sleep disorders.
a) PET
b) CT
c) X – rays
d) EEG
Answer:
d) EEG

Question 28.
Name the structure which connects the cerebral hemisphere
a) Choroid tissue
b) Corpus callosum
c) Neuroglia tissue
d) Pineal body
Answer:
b) Corpus callosum

Question 29.
Match and find out the correct sequence.

I. Frontal lobe	a. Reading
II. Parietal lobe	b. Hearing
III. Temporal lobe	c. Vision
IV. Occipital lobe	d. Memory

a) I-d II-a III-c IV-b
b) I-a II-c III-d IV-b
c) I-a II-b III-c IV-d
d) I-d II-a III-b IV-c
Answer:
d) I-d II-a III-b IV-c

Question 30.
Assertion: Statement A- The cortex of the cerebrum consists of grey matter.
Statement B- The reason for the grey matter is due to the presence of a non – myelinated sheath.
a) Statement A- True, Statement B – False
b) Statement A and B are true
c) Statement A- False the statement B- True.
d) Statement A and B are false.
Answer:
b) Statement A and B are true

Question 31.
Match and find the correct answer.
1. Broca area a. Perception of taste.
2. The pre-central gyrus b. Voluntary movements
3. The postcentral gyrus c. Aggression
4. Amygdala d. Speech function
a) I-a II-b III-c IV-d
b) I-d II-b III-c IV-a
c) I-d II-b Ill-a IV-c
d) I-a II-b III-c IV-d
Answer:
c) I-d II-b III-a IV-c

Question 32.
Assertion: Statement S – Brain controls emotions and feelings.
Statement T – There are no sensory neurons in the brain. Hence it cannot sense the pain.
a) Statement – S – True. Statement T – False
b) Statement – S – True Statement T – True
c) Statement – S – False Statement T – False
d) Statement S – False Statement T – True
Answer:
b) Statement – S – True Statement T – True

Question 33.
Which is considered as the relay centre for impulses
a) Medulla oblongata
b) Cerebrum
c) Hypothalamus
d) Thalamus
Answer:
d) Thalamus

Question 34.
Which indicates A, B, C and D in the following diagram

(a)
a) Temporal lobe
b) Frontal lobe
c) Parietal lobe
d) Cerebellum
(b)
a) Cerebellum
b) Parietal lobe
c) Temporal lobe
d) Frontal lobe
(c)
a) Cerebellum
b) Frontal lobe
c) Temporal lobe
d) Parietal lobe
(d)
a) Parietal lobe
b) Cerebellum
c) Frontal lobe
d) Temporal lobe
Answer:
(b)
a) Cerebellum
b) Parietal lobe
c) Temporal lobe
d) Frontal lobe

Question 35.
Find out the wrong statement.
a) The pre-central gyrus is called a motor strip.
b) The post-central gyrus is called a sensory strip.
c) The medulla oblongata controls respiration.
d) Wernicke area of the brain involved in the comprehension of speech.
Answer:
d) Wernicke area of the brain involved in the comprehension of speech.

Question 36.
The melatonin hormone which controls the sleep-wake cycle is secreted by
a) Pineal body
b) Thalamus
c) Hypothalamus
d) Medulla oblongata
Answer:
a) Pineal body

Question 37.
The lower portion of the midbrain consists of a pair of longitudinal nervous bands called
a) Emotional brain
b) Cerebral peduncles
c) Pons
d) Vermis
Answer:
b) Cerebral peduncles

Question 38.
The cauda equina presents in
a) Cerebrum
b) Thalamus
c) Hippo cambus
d) Spinal cord
Answer:
d) Spinal cord

Question 39.
Match and find the correct answer.
i) Thalamus – A) Respiration Gastric Pits.
ii) Hypothalamus – B) Vision Hearing
iii) Mid brain – C) Satiety centre
iv) Medulla oblongata – D) Learning memory

Answer:
a) i- D, ii – C, iii – B, iv – A

Question 40.
The cluster of nerve tissue in the cell body of neurons are called as
a) Gyri
b) Sulci
c) Vermis
d) Nerve ganglion.
Answer:
d) Nerve ganglion.

Question 41.
Find out the wrong pair
a) Cervical nerve – 8 pairs
b) Thoracic nerve – 12 pairs
c) Sacrum nerve – 4 pairs
d) Coccyx nerve – 1 pair
Answer:
c) Sacrum nerve – 4 pairs

Question 42.
What is the amount of cerebrospinal fluid secreted in an adult?
a) 500 ml
b) 150 ml
c) 400 ml
d) 250 ml
Answer:
b) 150 ml

Question 43.
The dissolved nicotene and alcohol in …………………… and ………………… minutes reach the brain.
a) 7 and 8 minutes
b) 6 and 7 minutes
c) 7 seconds and 6 minutes
d) 7 and 5 minutes.
Answer:
c) 7 seconds and 6 minutes

Question 44.
Name the structure that regulates homeostasis.
a) Mammillary body
b) Pineal body
c) Hypothalamus
d) Pituitary.
Answer:
a) Mammillary body

Question 45.
What is brain stem.
a) The structure seen in between spinal cord and cerebellum.
b) The region between Diencephalon and spinal cord
c) The region between medulla oblongata and cerebrum.
d) The region between medulla oblongata and mid-brain.
Answer:
b) The region between Diencephalon and spinal cord

Question 46.
What is the function of corpora quadri gemina?
a) Vision and hearing
b) Vision and homeostasis
c) Hearing and sense of touch
d) Hearing and vomiting.
Answer:
a) Vision and hearing

Question 47.
The region has seen in the mid of the cerebellum.
a) Corpus callosum
b) Pineal body
c) Pituitary
d) Vermis.
Answer:
d) Vermis.

Question 48.
What is the function of the interneuron?
a) Impulses from afferent and efferent neurons.
b) Impulses transmitted from efferent neurons to afferent neurons.
c) Impulses transmitted from central nervous system to receptor organs
d) From nerve transmitters to the spinal cord
Answer:
a) Impulses from afferent and efferent neurons.

Question 49.
Which part of the brain controls the unconditioned reflux?
a) The cortex of cerebrum
b) The medulla of brain
c) Cerebellum
d) pons.
Answer:
a) The cortex of cerebrum

Question 50.
……………………..pairs of nerves from cranium and …………………….. pairs of nerves from spinal cord.
a) 10 and 31
b) 12 and 31
c) 31 and 12
d) 31 and 10.
Answer:
b) 12 and 31

Question 51.
How much cerebrospinal fluid is synthesized in adults?
a) 200ml
b) 300ml
c) 150ml
d) 100ml.
Answer:
c) 150ml

Question 52.
What is the function of the vagus nerve?
a) It regulates the function of the abdominal structure
b) It regulates the speech and swallowing
c) It regulates the homeostasis of the body
d) Taste perception
Answer:
a) It regulates the function of the abdominal structure

Question 53.
Name the neural system which is auto functioning and self-governed.
a) Somatic neural system
b) Automatic neural system
c) Peripheral neural system
d) Limbic system.
Answer:
b) Automatic neural system

Question 54.
Name the structure that regulates the autonomic neural system.
a) Cerebrum
b) Cerebellum
c) Hypothalamus
d) Pons.
Answer:
c) Hypothalamus

Question 55.
Name the lubricating fluid which is secreted from the gland present at the base of the eyelashes.
a) Lacrymal gland
b) Cerebro-spinal fluid
c) Thymus gland
d) Sebaceous glands.
Answer:
d) Sebaceous glands.

Question 56.
Find the ABC and D in the diagram

a) a) Tear duct b) Sciera c) Iris d) Tear gland
b) a) Sciera b) Iris c) Tear gland d)Tear duct
c) a) Tear duct b) Iris c) Sclerad d)lTear duct
d) a) Tear gland b) Sclera c) Tear duct d) Iris.
Answer:
d) a) Tear gland b) Sclera c) Tear duct d) Iris.

Question 57.
Name the tissue which forms the non-vascular transparent coat cornea
a) Stratified squamous epithelium
b) Squamous epithelium
c) Canal of schlemm
d) All the above.
Answer:
a) Stratified squamous epithelium

Question 58.
Assertion: In bright light, the circular muscle in the iris contract so that the size of the pupil decreases and the light enter is regulated.
Reason: In the dim light, the radial muscle contract the pupil size increases, and less light enters the eye.
a) The assertion true but reason wrong
b) The assertion and reason are true
c) The assertion is true but reason does not explain the assertion
d) The assertion and reason are wrong.
Answer:
a) The assertion true but reason wrong

Question 59.
Name the yellow flat spot at the centre of the posterior region of the retina.
a) Blind spot
b) Scelera
c) Iris
d) Maculalutea
Answer:
d) Maculalutea

Question 60.
Which colour is perceived through chloropsin is sensitive to the medium wavelength of 530 mm
a) Red cones
b) Green cones
c) Blue cones
d) Red cells.
Answer:
b) Green cones

Question 61.
Name the glands that secrete tear.
a) Lacrymal gland
b) Sebaceous gland
c) Mandibular gland
d) Choroid plexues
Answer:
a) Lacrymal gland

Question 62.
…………………… enzyme is present in the tear.
a) Ptyalin
b) Lysozyme
c) Lipase
d) Erypsin.
Answer:
b) Lysozyme

Question 63.
Name the structure where more cones present.
a) Foveacenlralis
b) Maculalutea
c) Retina
d) Blind spot.
Answer:
a) Foveacenlralis

Question 64.
……………………………….. people can see the nearby object but cannot see the distant object.
a) Astigmatism
b) Presbiopia
c) Hypermetropia
d) Myopia
Answer:
d) Myopia

Question 65.
The concave lens helps in correct ………………. defect
a) Myopia
b) Hyper metropia
c) Astigmatism
d) Presbiopia
Answer:
a) Myopia

Question 66.
Which of the defect is depicted in the following diagram:

a) Emmetropia
b) Myopia
c) Hypermetropia
d) Astigmatism.
Answer:
b) Myopia

Question 67.
Match and find the correct sequence.

I. Concave	Surgery
II. Convex	Hypermetropia
III. Cataract	Astigmatism
IV. Cylindrical lens	Myopia

a) 1 -a 2-b 3-c 4-c
b) 1 -d 2-b 3-a 4-c
c) 1-d 2-a 3-a 4-b
d) 1-d 2-c 3-b 4-c
Answer:
b) 1 -d 2-b 3-a 4-c

Question 68.
Name the organ which regulates vision perception and homeostasis.
a) Ear
b) Eye
c) Cerebrum
d) Cerebellum.
Answer:
a) Ear

Question 69.
Find out the wrong pair.
a) Pinna – Eardrum
b) Oval window – Round window
c) Cochlea – Malleus
d) Perilymph – Endolymph
Answer:
c) Cochlea – Malleus

Question 70.
Indicate ABC and D in the Diagram.

a)
a) lncus
b) Eardrum
c) Organ of Corti
d) Tactoreal membrane.
b)
a) Organ of cortri
b) Incus
c) Tectoreal membrane
d)Eardrum
c)
a) Eardrum
b) Incus
c) Organ of Corti
d) Tectoreal membrane
d)
a) Eardrum
b) Incus
c) Tectoreal membrane
d) Organ of Corti
Answer:
d)
a) Eardrum
b) Incus
c) Tectoreal membrane
d) Organ of Corti

Question 71.
Find out the wrong statement.
a) The equilibrium receptor regions called maculae are involved in detecting the linear movement of the head.
b) The otoliths are made up of calcium
c) The crista ampullaris is to detect rotational movement of the head
d) Severe hearing loss occurs with frequent exposure to sound with intensities greater than50db.
(The 90db will affect the hearing).
Answer:
d) Severe hearing loss occurs with frequent exposure to sound with intensities greater than50db.

Question 72.
A person on his way to a village in a car for weekend holidays after finishing the office work. As he is very tired he begins to feel drowsy. He turns up the car stereo volume opens the car window and has sips ice-cold water.
How do these actions keep him awake? The increase in the number of sensory stimuli he received is relayed to the cerebral cortex which gets activated and prevents sleeping,
a) Spinal cord
b) Cerebrum
c) Medulla oblongata
d) Cerebellum.
Answer:
c) Medulla oblongata

Question 73.
Name the structure that connects the middle ear and pharynx.
a) Eustachian tube
b) Middle ear
c) Oval window
d) Organ of the cortii.
Answer:
a) Eustachian tube

Question 74.
Which part of the ear have bony labyrinth and a membranous labyrinth?
a) External ear
b) Inner ear
c) Middle ear
d) None of the above.
Answer:
b) Inner ear

Question 75.
Name the structure present in the bony labyrinth.
a) Cochlea, vestibule, maleus
b) Cochlea, vestibule Incus
c) Cochlea semicircular canals, stapes
d) Cochlea, vestibule semicircular canals.
Answer:
d) Cochlea, vestibule semicircular canals.

Question 76.
Where are the stereo cilia cells present in the ear?
a) Scala media
b) Scala vestibuli
c) Scala tymnani
d) Middle ear.
Answer:
a) Scala media

Question 77.
Match and find the correct sequence.

I. Meissner’s corpuscles	a) continuous pressure
II. Pacinian corpuscles	b) hardness, pain
III. Ruffini endings	c) temperature
IV. Krause and bulbs	d) light pressure

a) I-d, II-a, III-c, IV-d
b) I-d, II-b, III-c, V-a
c) I-d, II-b, Ill-a, IV-c
d) I-a, II-b, III-c, IV-d
Answer:
c) I-d, II-b, Ill-a, IV-c

Question 78.
When a cockroach tries to enter into the ear of a sleeping person, which one of the following process will start?
a) Unconditioned reflex
b) Neuro muscular fatigue
c) Stimulation of negative feedback mechanism
d) conditioned reflex
Answer:
a) Unconditioned reflex

Question 79.
What is the number of nerve cells present in the brain
a) 90 million
b) 100 billion
c) 90 billion
d) 100 million
Answer:
b) 100 billion

(2 Marks)

II. Write Very Short Answer

Question 1.
What are neurons? What are their functions?
Answer:
The structural and functional unit of the nervous system is neurons. They detect, receive, process, and transmit different kinds of stimuli. They are sensory, motor, and autonomic in functions.

Question 2.
What is meant by Neuroglia? What are its functions?
Answer:
The non-nervous special cells called neuroglia from the supporting cells of the nervous tissue.

1. Providing nourishment to the neurons
2. Repairing the injured tissues
3. It helps in dividing and regeneration
4. Acting as phagocyte cells to engulf the foreign particles at the time of any injury to the brain.

Question 3.
Differentiate the functions of myelinated and non-myelinated neurons.
Answer:

Myelinated neuron	Non-myelinated neuron
They conduct impulses rapidly	Conduct impulse slowly
Present in the medulla	Seen in the cortex of the cerebrum.

Question 4.
What are the functions of neuroglia?
Answer:

1. They provide nourishment to the surrounding neurons.
2. They involve in the memory process.
3. They repair the injured tissue due to their dividing and regenerating capacity.
4. They engulf the foreign particles at the time of any injury to the brain.

Question 5.
What is meant by nerve impulses?
Answer:
A nerve impulse is a series of electrical impulses which travel along with the nerve fibre.

Question 6.
What is a neurilemma?
Answer:
The plasma membrane covering the neuron is the neurilemma.

Question 7.
What is meant by threshold potential?
Answer:
During depolarization when enough Na⁺ ions enter the cell the action potential reaches a certain level called threshold potential. (-55 mV)

Question 8.
What are Nodes of Ranvier?
Answer:
The Schwann cells covering the axon are not continuous. There are gaps in the myelin sheath between adjacent Schwann cells. These gaps are called Nodes of Ranvier.

Question 9.
What is meant by all or none principle?
Answer:
The action potential occurs in response to a threshold stimulus but does not occur at sub-threshold stimuli. This is called the all or none principle.

Question 10.
What is Synaptic Cleft?
Answer:
A small gap between the pre and post-synaptic membranes is called Synaptic Cleft. It forms a structural gap and a functional bridge between neurons.

Question 11.
What are meninges?
Answer:
The brain is covered by the outer Duramater, the median Arachnoid mater, and the inner Piamater. These membranes are called meninges.

Question 12.
What is meant by lazy gate?
Answer:
During hyper polarization the K⁺ion gates are more permeable to K⁺ even after reaching threshold level it closes slowly hence called lazy gates.

Question 13.
What is subarachnoid space?
Answer:
The space between the pia mater and arachnoid mater is called subarachnoid space.

Question 14.
What is meant by repolarisation?
Answer:
When the membrane reaches the spike potential the potassium ions K⁺ efflux from the axolemma and hence form negative potential. This is called repolarisation.

Question 15.
What are mammillary bodies?
Answer:
A pair of small rounded body in the hypothalamus is called mammillary bodies. These are involved in olfactory reflexes and emotional response to odour.

Question 16.
Which decides the speed of the conduction of a nerve impulse?
Answer:

• The conduction speed of a nerve impulse depends on the diameter of axon.
• The greater the axon’s diameter the faster is the conduction.

Question 17.
What is septum pellucidum?
Answer:
A thin membrane which separates the lateral ventricles I and II are called the septum pellucidum.

Question 18.
What is the difference between sub durai space and sub arachnoid space
Answer:

Sub durai space	Sub arachnoid space
A narrow sub dural space present in between arachnoid and durameter	The space between the arachnoid membrane and piameter.

Question 19.
What is meant by sulcus and gyrus? What is its functions.
Answer:

• Gyri – The convolution seen in the cerebrum.
• Sulci – The shallow grooves increase the surface area of the cerebral cortex.

Question 20.
What is Choroid plexus?
Answer:
The choroid plexus is a network of blood capillaries found in the roof of the ventricles. These form cerebrospinal fluid from the blood.

Question 21.
What is the function of proca?
Answer:
It involves speech function.

Question 22.
What are Cranial nerves?
Answer:
The 12 pairs of nerves which arise from the brain are called cranial nerves.

Question 23.
Which part of the cerebrum is called a sheet of emotions?
Answer:
The cortex of parietal occipital and temporal.

Question 24.
What is a mixed nerve?
Answer:
A nerve which contains both sensory (afferent) and motor (efferent) fibres is called a mixed nerve.

Question 25.
What are Exteroceptors?
Answer:
Exteroceptors are located at or near the surface of the body. These are sensitive to external stimuli and receive sensory impulses for hearing, vision, touch, taste, and smell.

Question 26.
Where is the pineal body situated? What are its functions?
Answer:
It is situated behind the choroid plexus the epithalamus forms a short stalk
Functions: The melotoxin secreted by the pineal body regulates the sleep wake cycle.

Question 27.
What are Lacrymal glands?
Answer:
Tears secreting glands located in the upper lateral region of each orbit are called Lacrymal glands.

Question 28.
What is meant by corpus callosum?
Answer:
The two hemispheres of the cerebrum are connected with the nerve band known as the corpus callosum.

Question 29.
What is meant by brain stem? What are its parts?
Answer:
The region between the spinal cord and diencephalon.

1. Mid-brain
2. Pons varoli
3. Medulla oblongata

Question 30.
What is meant by corpora quadri gemina? What are its functions?
Answer:

• The four papillae are seen on the dorsal side of mid brain.
• Perception of vision and hearing

Question 31.
What is macula lutea?
Answer:
The yellow flat spot at the centre of the posterior region of the retina is called macula lutea. It is responsible for sharp detailed vision.

Question 32.
What are the functions of the cerebellum?
Answer:
The cerebellum controls and coordinates muscular movements and body equilibrium.

Question 33.
What is meant by receptors?
Answer:
The organ which made us aware of changes occur in our surrounding is called receptors.

Question 34.
What is meant by a voluntary neural system?
Answer:
It is the part of the peripheral neural system associated with the voluntary control of body movements via skeletal muscles

Question 35.
Name the bacteriocidal substance present in the tears? Where is it seen? Name its secretion?
Answer:

• Lysosome enzyme
• Seen in tears.
• Lacrymal glands. 1ml is secreted in a day.

Question 36.
What is crista ampullaris?
Answer:
The lower end of each semicircular canal is swollen and it is called the ampulla. Each ampulla has a sensory area known as crista ampullar.

Question 37.
What are cerebral peduncles?
Answer:
The region between the diencephalon and the pons is called the midbrain. It consists of a pair of longitudinal bands of nervous tissue called cerebral peduncles.

Question 38.
What is a brain stem? What are its parts?
Answer:
It is the part of the brain between the spinal cord and the diencephalon.
Organs: Mid-brain, Pons, Medulla oblongata

Question 39.
What are Krause end bulbs?
Answer:
These are thermoreceptors of the skin that sense temperature.

Question 40.
Where is the enlargement region seen in the spinal cord?
Answer:

• Cervical enlargement
• Lumbar enlargement.

Question 41.
What is meant by reflex action?
Answer:

• When a very quick response is needed the spinal cord can effect motor initiation as the brain and brings about an effect.
• This rapid action by the spinal cord is called reflex action.

Question 42.
What is meant by the peripheral nervous system?
Answer:
All nervous tissue outside the CNS is the nervous system.

Question 43.
What is meant by mixed nerve?
Answer:
Each spinal nerve is a mixed nerve containing both afferent (sensory) and efferent (motor) fibers.

Question 44.
What is meant by pre ganglionic neuron?
Answer:
Its cell body is in the brain or spinal card. Its myelinated axon exits the CNS as part of cranial or spinal nerve and end in an autonomic ganglion.

Question 45.
What is autonomic ganglion?
Answer:
The axons of pre ganglionic neuron and cell bodies of post ganglionic neuron includes autonomic ganglion.

Question 46.
What is post ganglionic neuron?
Answer:
It conveys nerve impulses from autonomic ganglia to visceral effector organs.

Question 47.
What are the two branches of the autonomous nervous system?
Answer:

1. Sympathetic neural system
2. Parasympathetic neural system.
3. varying distances is called accommodation.

Question 48.
Give short notes on Lacrymal glands?
Answer:

• The tear secreting glands are known as Lacrymal glands.
• 1ml of tear is secreted in a day.
• Tear salts, mucous and lysozyme enzyme to destroy bacteria.

Question 49.
What is conjunctiva?
Answer:
It is a thin protective mucous membrane found lining the outer surface of the eye ball.

Question 50.
Dilation and congestion of the blood vessels due to local irritation or infections. What is the disease? When will it occur?
Answer:

• Conjunctivitis or madras eye.
• Irritation or infection are the cause of bloodshot eye.

Question 51.
What is sty?
Answer:
Infection of ciliary glands by bacteria causes painful pus-filled swelling called a sty.

Question 52.
What are the three types of cells present in the neural retina?
Answer:

• Photo receptor cell
• Cones
• Rods
• Bipolar and ganglion cells.

Question 53.
What is a cataract?
Answer:
Due to the changes in nature of protein the lens become an opaque called cataract.

Question 54.
What is aqueous humour and vitreous humour
Answer:

• Aqueous humour – The fluid filled in between the cornea and iris.
• Vitreous humour – Fluid filled in between lens and retina.

Question 55.
Give notes on lens fibres?
Answer:
Eye lens is transparent and biconvex made up of long columnar epithelial cells called lens fibre, these cells are formed of crystalline protein.

Question 56.
What are the three layers of eyeball?
Answer:

1. Sclera – Outer coat
2. Choroid – Pigmented middle layer
3. Retina – Inner most layer

Question 58.
What is meant by maculae lutea?
Answer:
The yellow flat spot at the centre of the posterior region of the retina is called macula lutea. It is responsible for sharp detailed vision.

Question 59.
What is fovea centralis?
Answer:
A small depression present in the centre of the yellow spot is called fovea centralis which contains only cones.

Question 60.
What is a blind spot?
Answer:
The optic nerves and the retinal blood vessels enter the eye slightly below the posterior pole whichis devoid of photoreceptors is called a blind spot.

Question 61.
Why there is no cornea rejection during cornea transplantation?
Answer:

• There is little or no possibility of cornea rejection.
• This is because the cornea does not have blood vessels.

Question 62.
What are the three ear ossicles?
Answer:

1. Malleus – hammer bone
2. Incus – anvil bone
3. Stapes – stirrup bone

Question 63.
What are the three chambers of cochlea?
Answer:

1. Scala vestibule
2. Scala tympani
3. Scala media

Question 64.
What is tectorial membrane?
Answer:
A roof-like structure over hanging the organ of Corti throughout its length with the stiff gel membrane called tectorial membrane.

Question 65.
Name the receptors which are excited by airborne chemicals that dissolve in fluids?
Answer:
The receptors for taste and smell are the chemo receptors

Question 66.
What is a tactile Merkel disc?
Answer:
It is the light touch receptor lying in the deeper layer of the epidermis.

Question 67.
What are the structures present in the membranous labyrinth?
Answer:

• Cochlea
• Vestibule
• Semi circular canals

Question 68.
What are the three chambers of cochlea? Name the membrane which separates these chambers?
Answer:

1. Scala vestibuli
2. Scala tympanii
3. Scala media

Separating membranes
Reisner’s membrane. It separates scala vestibuli from scala media
Basilar membrane. It separates scala media from scala tympani.

Question 69.
What is meant by stereo cilia?
Answer:

• The organ of corti contains numerous hair cells on the basilar membrane.
• Protruding from the apical part of each hair cell is hair-like structures called stereo cilia.

Question 70.
What is proprioception?
Answer:
The ability to provide information about the position and movements of the body is proprioception.

Question 71.
What is meant by vestibular system?
Answer:
This is the organ of balance this system is composed of fluid-filled sacs and tubules.

Question 72.
Give notes on utriculus and sacculus?
Answer:
The utricle and saccule contain equilibrium receptor regions called maculae that are involved in detecting the linear movement of the head.

Question 73.
What is otolith?
Answer:

• Maculae contains hair cells. These hair cells contain calcareous particles called otoliths.
• It increases the inertia.

Question 74.
What are ampullae?
Answer:
At one end of each semicircular canal at its lower end has a swollen area called ampulla Each ampulla has sensory hair cells and supporting cells called crista ampullaris. The function is to detect the rotational movement of the head.

Question 75.
Give the name of balancing structures which perform the following action.

• Linear movement of the head
• Changes occurring in body position.
• Rotational movement of the head

Answer:

• Maculae
• Vestibular system
• Crista ampularis

Question 76.
What is the unit of sound? Give notes on our ability of sound perception?
Answer:

• The intensity of sound is measured in decibels. (dB)
• 0-50 dB is the threshold of hearing for normal ear.
• Prolonged exposure to sound with intensities greater than 90dB causes hearing loss.

Question 77.
What are chemo receptors?
Answer:

• The receptors for taste and smell are the chemo receptors
• The smell receptors are excited by air borne chemicals that dissolve in fluids.

Question 78.
What are olfactory organs? Where are they situated?
Answer:

• The yellow coloured patches of olfactory epithelium form the olfactory organs.
• They are located on the roof of the nasal cavity.

Question 79.
What are papillae?
Answer:
The tongue is provided with many small projection called papillae which is responsible for taste.

Question 80.
Give notes on taste buds.
Answer:

• The taste bud cells are subjected to huge amounts of friction because of their location and are routinely burned by hot foods.
• These are the most dynamic cells in the body and replaced every seven to ten days.

 

(3 Marks)

III. Short Answers

Question 1.
What are the three main functions of nervous system.
Answer:

• Sensory functions: It receives sensory input from internal and external environment.
  Motor functions: It transmits motor commands from the brain to the skeletal and muscular system.
• Autonomic functions: Reflex actions.

Question 2.
How do we classify neurons on the basis of its functions.
Answer:

• Afferent neurons – That take sensory impulses to the central nervous system from the sensory organs.
• Efferent neurons – That carry motor impulses from CNS to the effector organ.
• Inter neurons – That lie entirely within the CNS between the afferent and efferent neurons.

Question 3.
What is meant by depolarisation?
Answer:

• The inside of the axolemma becomes positively charged and negatively charged outside.
  This reversal of electrical charge is called depolarisation.

Question 4.
How are nerve impulses transmitted?
Answer:

• Inner to the axolemma the cytoplasm contains the infra cellular fluid with large amounts of potassium and magnesium phosphate with negatively charged proteins and other organic molecules.
• Outside the axolemma contains large amounts of sodium chloride bicarbonates CO² and metabolic wastes
• Due to the charged particles present in the inner and outside of the axolemma are responsible for the conduction of nervous impulses.

Question 5.
What is meant by repolarisation?
Answer:

• When the axolemma reaches the spike potential the sodium voltage – gate closes and potassium – voltage gate opens.
• It checks influx of Na⁺ ions and initiation the efflux of K ions which lowers the number of positive ions within the cell. Thus the potential falls back towards the resting potential.

• The reversal of membrane potential inside the axolemma to negative occurs clue to efflux of K⁺ ions. This is called repolarisation.

Question 6.
What is meant by hyper polarisation?
Answer:

• If repolarisation becomes more negative than the resting potential -70 mV to about -90 mV.
• It is called hyper polarisation. During this K⁺ ion, gate is more permeable to K⁺ even after reaching the threshold level as it closes slowly hence called lazy gates.

• The membrane potential return to its original resting state when K⁺ ion channel close completely.
• During hyper polarization the Na⁺ voltage gate remains closed.

Question 7.
Give an account of the conduction speed of a nerve impulse.
Answer:

• If the axon’s diameter is greater the conduction will be faster.
• The myelinated axon conducts the impulse faster than the non-myelinated axon.

Question 8.
What is meant by saltatory conduction?
Answer:
The myelinated axon conduction the impulse faster than the non – myelinated axon.
The voltage gated Na⁺ and K⁺ channels are concentrated at the nodes of Ranvier as a result the impulse jumps from node to node. This is called saltatory conduction.

Question 9.
Give an account of the membranes (meninges) of brain?
Answer:
Brain is covered by three cranial meninges.

1. The outer thicker layer is duramater which lines the inner surface of the cranial cavity.
2. The inner most layer which is adhered to the brain is the piameter.
3. The median thin layer is arachnoid mater by a narrow subdural space.
4. The piameter is separated from the arachnoid mater by the subarachnoid space.

Question 10.
List out the functions of brain lobes?
Answer:

Structure	Function
Frontal	Behaviour intelligence memory movement
Parietal	Language reading sensation
Temporal	Speech hearing memory
Occipital	Visual processing

Question 11.
Why is thalamus considered as a important relay centre for impulse?
Answer:

• It serves as a relay centre for impulses between the spinal and brain and cerebrum.
• Information is sorted and edited.
• It plays a key role in learning and memory.
• It is a co-ordinating centre for sensory and motor signaling.

Question 12.
Why there may be a death due to the affectation of medulla oblongata?
Answer:

• Medulla controls cardio-vascular reflexes respiration and gastric secretions.
• If medulla is getting affected the circulation and respiration is affected.
• That may cause a death of a person.

Question 13.
Give notes on mid brain?
Answer:

• The midbrain is located between the diencephalon and the pons.
• The lower portion of the mid-brain consists of a pair of longitudinal bands of nervous tissue called cerebral peduncles.
• This relay impulses back and forth between cerebrum cerebellum pons and medulla.
• The dorsal position of the mid Brain consist of four rounded bodies called corpora quadrigemina which acts as a reflex center for vision and hearing.

Question 14.
What are the features we develop when there is a functional deficiency of serotonin and nor epinephrine?
Answer:
Features:

• negative mood
• loss of interest
• an in ability to experience pleasure
• suicidal tendencies.

Drugs:
Anti depressant drug can treat all this features.

Question 15.
Give notes on cerebro spinal fluid?
Answer:

• 150ml of cerebro spinal fluid is secreted in an adult.
• 500ml of cerebro spinal fluid is secreted in a day.
• Every 8 hours this fluid is rejuvenated.
• The choroid plexus carries harmful metabolic wastes from the brain to the blood.

Question 16.
Based on their position how the receptors are classified?
Answer:
1. Exteroceptors: They are located at the surface of the body.
These senses the hearing vision touch taste and smell.

2. Introceptors: They are located in the visceral organs and blood vessels.
They are sensitive to internal stimuli.

3. Prerprioceptors:
They provide information about position and movements of the body.

Question 17.
Your friend is returning home after his visit to USA. All at home are waiting for his arrival.
How would you feel? State the division of ANS that predominates and mention few changes take place in your body?
Answer:

• The sympathetic and parasympathetic neural system are is mainly involved.
• On seeing his friend out of the happiness his autonomic nervous system is stimulated and he gets tears in his eyes.
• After sometime the parasympathetic stops the secretion of tears.

Question 18.
What is meant by depression? What are its symptoms?
Answer:

• Depression is a functional deficiency of serotonin and nor epinephrine.
• This disorder is characterized by a pervasive negative mood, loss of interest an inability to experience pleasure and suicidal tendencies.

Question 19.
When dust falls on our eyes like eyelids close immediately not waiting for our willingness, on touching a hot pan the hand is with drawn rapidly. Do you know how this happens?
Answer:
Reflex axon.
When a very quick response is needed the spinal cord can effect motor initiation as the brain and brings about an effect it is due to fast action of spinal cord.

Question 20.
What are the differences between conditioned and unconditioned reflex.
Answer:

Unconditioned reflex	Conditioned reflex
In born reflex for an unconditioned stimulus.	It’s response to a stimulus acquired by learning.
It does not need any past experience or training	Does not naturally exists in animals.
Eg: Blinking of an eye when a dust particle about to fall in it	Eg: Excitement of salivary gland on seeing a food

Question 21.
What is the difference between exteroceptors and interoceptors.
Answer:

Exteroceptors	Interoceptors
Located at or near the surface of the body	They are located in the visceral organs and blood vessels.
These receive impulses from hearing vision touch taste and smell.	They are sensitive to internal stimuli.

Question 22.
Where are lens fiber seen? What is the substance that fills it?
Answer:

• The lens is a transparent biconvex structure made up of slender columnar epithelial cells.
• These cells are called as lens fibre.
• These cells are formed of crystaline protein.

Question 23.
What is meant by accommodation of eye? List the structures that are involved in this process?
Answer:

• The ability of the eyes to focus objects at varying distances is called accommodation.
• This is achieved by suspensory ligament ciliary muscle and ciliary body

Question 24.
Name the structures that helps in fixing eyes in the eye ball?
Answer:
Eye is held in its position with the help of six extrinsic muscles. They are

• Superior
• Interior
• Lateral
• Median rectus muscle
• Superior oblique
• Inferior oblique

Question 25.
Name the accessory structure which protects eye?
Answer:

• Eye lashes and the eye brows
• They help to protect the eyeballs from foreign objects, perspiration and from direct sunrays.
• Sebaceous glands or ciliary glands.
• They secrete a lubricating fluid.
• Lacrymal glands.
• Secrete tears.
• Tears contain salts mucus and lysozyme enzyme to destroy bacteria.

Question 26.
Give an account of aqueous humour?
Answer:

• It supplies nutrients and oxygen to the lens cornea and retinal cells.
• It is produced and drained at same rate.
• It maintains a constant infra ocular pressure of about 16 mmHg.

Question 27.
Give short notes on glaucoma.
Answer:
Any block in the canal of Schlemm increases the intra ocular pressure of aqueous humour and leads to “glaucoma when the optic nerve and the retina are compressed due to pressure.

Question 28.
Name the detects of detraction.
Answer:

• Myopia
• Hyper metropia
• Astigmatism
• Cataract

Question 29.
Give notes on pigments of colour vision
Answer:

• Redcones. It contains visual pigment erythropsin which is sensitive to long wavelength close to 560 nm.
• Green cones – It has a pigment chloropsin which is sensitive to medium wavelength of 530 nm.
• Blue cones – It has a pigment which is sensitive to short wavelength of 420 nm.

Question 30.
What is the difference between conducting hearing loss and neuro-sensory hearing loss?
Answer:

Conducting Hearing loss	Neuro sensory
This defect is due to the blockage of ear canal with ear wax	The defect may be in the organ of cortii
Rupture of ear	The auditory nerve
Middle ear infection with fluid accumulation restriction of ossicular movement	In the ascending auditory pathways or auditory cortex

Question 31.
Give short notes on melanin.
Answer:

• Melanocytes synthesize melanin.
• It gives colour to skin and protects it from the sun.
• Vitiligo is a condition in which the melanin pigment is lost from the areas of the skin causing white patches.
• The leukoderma appears when melanocytes fails to synthesis melanin pigment.

Question 32.
What is meant by the proprioception?
Answer:

• Balance is part of a sense called proprioception.
• It is the ability to sense the position orientation and movement of the body.

Question 33.
Which is the fastest renewable cells in the body? How is it affected?
Answer:
Taste buds

• Taste buds are subjected to huge amounts of friction because of their location and are routinely burned by hot foods.
• These cells are replaced every 7-10 days.

Question 34.
Name the disease which can affect people of any age gender or ethnic group. This is not the contagious disease?
Answer:
Leucoderma is a condition in which the melanin pigment is lost from areas of the skin causing white patches.

Question 35.
What are meissner’s corpuscles?
Answer:

• These are small light pressure receptors found just beneath the epidermis in the dermal papillae.
• They are numerous in hairless skin areas such as finger tips and soles of the feat.

(5 Marks)

IV. Brief Answers

Question 1.
Describe structure of a neuron.
Answer:
Neuron is composed of three region.

1. Cell body
2. Dendrites
3. axon.

Cell body:
The cell body is spherical. There is no centriole.
The plasma membrane covering the neuron is called neurilemma and axon is axolemma.

Dendrites:
The repeatedly branched short fibres coming out of the cell bod dendrites which transmit impulses towards the cell body in it’s cytoplasm Nissl’s granules are present.

Axon:
It is a long fibre that arises from a cone shaped area of the cell body. There is no golgi bodies and Nissis granules in its cytoplasm.
The axon of peripheral nerves is surrounded by Schwann’s cells to form myelin sheath. The myelin sheath is not continuous. There are gaps in the myelin sheath between an adjacent Schwann cells called nodes of Ranvier.
Each branch at the distal end of the axon terminates into a knob like structure called synaptic knob which possesses synaptic vesicles filled with transmitters. The axon transmits nerve impulses away from the body to neuro muscular junction. The myelinated nerve cell transmits impulses faster than non – myelinated nerve cells.

Question 2.
Describe about the different types of neuron with diagram?
Answer:
1. Multi polar neurons:
They have many processes with one axon and two or more dendrites.

2. Bipolar neurons:
They have two processes with one axon and one dendrites.
These are found in the retina of the eye, inner ear and the olfactory area of the brain.

3. Unipolar neurons:
They have a single short process and one axon.

Question 3.
Give an account of Ionic channels in the axolemma?
Answer:
Ionic channels:

1. Leakage channels
2.  Ligand – gated channels
3. Voltage-gated channels.

1. Leakage channels:

• • These channels are always remain open.
  • K⁺ leakage channels are more in number than the Na⁺ leakage channels.
  • Sarco lemma has greater permeability to k⁺ icons than Na⁺ icons
  • These icons keep moving continuously to maintain the potential continuously to maintain the
  • potential difference across the axo lemma.

2. Ligand – gated channels:
These are chemic called gated channels which open or close in response to a chemical stimuli.

• They are located between the pre synaptic membrane of the first axon and post synaptic membrane of the second.
• The neurotransmitter acetylcholine opens ligand channels that allow Na⁺ and Ca⁺⁺ ions diffuse inward and K⁺ icon diffuse outward.

Voltage-gated channels:
Answer:
This channels open in response to a physical stimulus in the form of vibration such as touch and pressure.

• Sodium Voltage gated channels.
• Potassium Voltage gated channels.

Question 4.
Explain the transmission of nerve impulses?
Answer:
The transmission of impulse involves two main phases; Resting membrane potential and Action membrane potential. Resting membrane Potential: The electrical potential difference across the plasma membrane of a resting neuron is called the resting potential during which the interior of the cell is negative due to greater efflux of K⁺ outside the cell than Na⁺ influx into the cell.

When the axon is not conducting any impulses i.e. in resting condition, the axon membrane is more permeable to K⁺ and less permeable to Na⁺ ions, whereas it remains impermeable to negatively charge protein ions. The axoplasm contains high concentration of K⁺ and negatively charged proteins and low concentration of Na⁺ ions.

In contrast, fluid outside the axon (ECF) contains a low concentration of K+ and a high concentration of Na+, and this forms a concentration gradient. This ionic gradient across the resting membrane is maintained by ATP driven Sodium-Potassium pump, which exchanges 3Na+ outwards for 2K+ into the cells.

In this state, the cell membrane is said to be polarized. In neurons, the resting membrane potential ranges from -40 mV to -90 mV, and its normal value is -70 mV. The minus sign indicates that the inside of the cell is negative with respect to the outside.

Action membrane potential:
An action potential occurs when a neuron sends information down an axon, away from the cell body. It includes the following phases, depolarization, repolarization, and hyperpolarization.

Depolarization – Reversal of polarity:
When a nerve fibre is stimulated, sodium voltage-gated opens and makes the axolemma permeable to Na+ ions; meanwhile the potassium voltage-gated closes. As a result, the rate of flow of Na⁺ ions into the axoplasm exceeds the rate of flow of K⁺ ions to the outside fluid [ECF]. Therefore, the axolemma becomes positively charged inside and negatively charged outside.

This reversal of electrical charge is called Depolarization. During depolarization, when enough Na⁺ ions enter the cell, the action potential reaches a certain level, called threshold potential [-55 mV], The particular stimulus which is able to bring the membrane potential to the threshold is called threshold stimulus.

The action potential occurs in response to a threshold stimulus but does not occur at subthreshold stimuli. This is called the all or none principle. Due to the rapid influx of Na⁺ ions, the membrane potential shoots rapidly up to + 45 mV which is called the Spike potential.

Repolarisation [Falling Phase]: When the membrane reaches the spike potential, the sodium voltage-gated closes, and the potassium voltage-gated opens. It checks influx of Na⁺ ions and initiates the efflux of K⁺ ions which lowers the number of positive ions within the cell.’Thus, .the potential falls back towards the resting potential. The reversal of membrane potential inside the axolemma to negative occurs due to the efflux of K+ ions. This is called Repolarisation.

Hyperpolarization:
If repolarization becomes more negative than the resting potential -70 mV to about -90 mV, it is called Hyperpolarization. During this, K⁺ ion gates are more permeable to K+ even after reaching the threshold level as it closes slowly; hence called Lazy gates. The membrane potential returns to its original resting state when K⁺ ion channels close completely. During hyperpolarization, the Na⁺ voltage gate remains closed.

Conduction Speed of a nerve impulse: The conduction speed of a nerve impulse depends on the diameter of axon. The greater the axon’s diameter, the faster is the conduction.. The myelinated axon conducts the impulse faster than the non-myelinated axon.

The voltage-gated Na⁺ and K⁺ channels are concentrated at the nodes of Ranvier. As a result, the impulse jumps node to node, rather than traveling the entire length of the nerve fibre. This mechanism of conduction is called Saltatory Conduction. Nerve impulses travel at the speed of 1-300 m/s.

Question 5.
a) What is meant by action – membrane potential?
b) What is Depolarisation?
Answer:
a) An action potential occurs when a neuron sends information down an axon away from the cell body.
b) When a nerve fibre is stimulated sodium voltage gate opens and makes the axo lemma permeable to Na⁺⁺ and the potassium voltage gate closes and potassium is getting out of the axo lemma. The concentration reduces

• The axo lemma becomes positively charged inside and negatively charged outside.
• This reversal of electrical charge is called depolarisation potential reaches level called threshold potential (-55mV)
• The stimulus which bring this threshold potential is called threshold stimulus.
• The action potential occur in response to a threshold stimulus but does not occur at subthreshold stimuli. This is called all or none principle.
• Due to the rapid influx of Na⁺ ions the membrane potential shoots rapidly up to +45mV which is called the spike potential.

Question 6.
What is synapsis?
Answer:

• The junction between two neurons is called a synapses through which a nerve impulse is transmitted,
• The first neuron involved in the synapse forms the pre synaptic neuron and the second neuron is the post – synaptic neuron
• A small gap between the two neuron is synaptic cleft.
• The axon terminals contain synaptic vesicles filled with neurotransmitters.
• When an impulse arrives at the axon terminals it depolorizes the pre – synaptic membrane opening the voltage gated calcium channels.
• Influx of calcium ions stimulates the synaptic vesicles toward the pre – synaptic membrane and fuse with it.
• In the neurilemma the vesicles release their neurotransmitters into the synaptic cleft by exocytosis.
• The released neurotransmitters bind to their specific receptors.
• The entry of the ions can generate a new potential in the post synaptic neuron.
• This excitatory post – synaptic potential causes depolarisation and in inhibitory post – synaptic potential causes hyperpolarisation.

Question 7.
In the following diagram indicate
Answer:
(A) – Frontal
(B) – parietal
(C) – occipital
(D) – temporal lobe

Question 8.
Describe the structure of human brain with a diagram?
Answer:

• The brain is located in the cranial cavity and it is covered by three cranial membranes.
• The outer layer — durameter the inner most layer piameter and the median thin layer arachnoid. The brain is divided into three major regions. Fore brain, Mid-brain, Hind

• It comprises of cerebrum and diencephalon.
• Tire cerebral cortex is composed of grey and unmyelinated nerve cells.
• The medulla is composed of white mater.
• The surface of the cerebrum shows many convolutions and grooves. The folds are called gyri and the shallow groove is sulci.

There are eight lobes in cerebrum.
A pair of frontals, parietals temporals and occipital lobes.
The longitudinal fissure divides the cerebrum longitudinally into two hemispheres The hemispheres are connected by a tract of nerve fibres called corpus callosum.
Cerebral cortex has three functional areas

Sensory areas:
It occurs in the parietal temporal and occipital lobes of the cortex.

Motor areas:
This controls voluntary muscular movement which lies in the posterior part of the frontal iobes.

Association area:
It lies in between cortex and diencephalan This involves in memory communication learning and reasoning.

Question 9.
Explain the structure of the forebrain?
Answer:
The forebrain comprises the following regions: Cerebrum and Diencephalon. The cerebrum is the ‘seat of intelligence’ and forms the major part of the brain. The cerebrum consists of an outer cortex, inner medulla and basal nuclei.

The superficial region of the cerebrum is called the cerebral cortex, which looks grey due to the presence of unmyelinated nerve cells. Cerebral cortex – consists of the neuronal cell body, dendrites, associated glial and blood vessels.

The surface of the cerebrum shows many convolutions (folds) and grooves. The folds are called gyri, the shallow grooves between the gyri are called sulci and deep grooves are called fissures. These sulci and gyri increase the surface area of the cerebral cortex. Several sulci divide the cerebrum into eight lobes; a pair of frontals, parietals, temporals and occipital lobes.

A median longitudinal fissure divides the cerebrum longitudinally into two cerebral hemispheres. A transverse fissure separates the cerebral hemispheres from the cerebellum.

The hemispheres are connected by a tract of nerve fibres called corpus callosum. Cerebral cortex has three functional areas namely sensory areas occur in the parietal, temporal and occipital lobes of the cortex. They receive and interpret the sensory impulses.

Motor area of the cortex which controls voluntary muscular movements lies in the posterior part of the frontal lobes. The areas other than sensory and motor areas are called Association areas that deal with integrative functions such as memory, communications, learning and reasoning. Inner to the cortex is medulla which is white in colour and acts as a nerve tract between the cortex and the diencephalon.

Diencephalon consists largely of following three paired structures. The epithalamus forms the roof of the diencephalon and it is a non-nervous tissue. The anterior part of the epithalamus is vascular and folded to form the choroid plexus. Just behind the choroid plexus, the epithalamus forms a short stalk that ends in a rounded body called pineal body which secretes the hormone, melatonin which regulates the sleep and wake cycle.

Thalamus is composed of grey matter which serves as a relay centre for impulses between the spinal cord, brain stem and cerebrum. Within the thalamus, information is sorted and edited and plays a key role in learning and memory. It is a major coordinating centre for sensory and motor signaling.

Hypothalamus forms the floor of the diencephalon. The downward extension of the hypothalamus, the infundibulum connects the hypothalamus with the pituitary gland. The hypothalamus contains a pair of small rounded body called mammillary bodies that are involved in olfactory reflexes and emotional responses to odour.

Hypothalamus maintains homeostasis and has many centres which control the body temperature, urge for eating and drinking. It also contains a group of neurosecretory cells which secrete the hypothalamic hormones. Hypothalamus also acts as the satiety centre.

Limbic system: The inner part of the cerebral hemisphere constitutes the limbic system. The main components of limbic system are olfactory bulbs, cingulate gyrus, mammillary body, amygdala, hippocampus and hypothalamus.

The limbic system is called the ‘emotional brain’ because it plays a primary role in the regulation of pleasure, pain, anger, fear, sexual feeling and affection. The hippocampus and amygdala also play a role in memory. Brain stem is the part of the brain between the spinal cord and the diencephalon. It consists of mid-brain, pons varolii and medulla oblongata.

Question 10.
Describe the structures of diencephalon?
Answer:
Epithalamus:

• It is a non – nervous tissue.
• The anterior part of epithalamus is vascular and folded to form the anterior choroid plexus.
• The epithalamus forms a short stalk which ends in a rounded body called pineal body.
• This secretes the hormone melotonin which regulates sleep and wake cycle.

Thalamus:

• It is formed of grey matter
• It serves as a relay centre for impulses between the spinal cord brain stem and cerebrum.
• It plays a key role in learning and memory.
• It is a major co-ordinating centre for sensory and motor signalling.

Hypothalamus:

• It forms the floor of the diencephalon.
• It has a pair of small rounded body called mammillary bodies
• It involves in olfactory reflexes and emotional responses to odour.
• It maintains homeostasis.
• It controls the body temperature.
• Urge for eating and drinking.
• It also contains a group of neuro secretory cells which secrete the hypothalamic hormones.
• It also acts as the satiety centre.

Question 11.
Explain the structure of the Hindbrain?
Answer:
Rhombencephalon forms the hindbrain. It comprises of cerebellum, pons varolii and medulla oblongata. The cerebellum is the second largest part of the brain. It consists of two cerebellar hemispheres and a central worm-shaped part, the vermis. The cerebellum controls and coordinates muscular movements and body equilibrium. Any damage to the cerebellum often results in uncoordinated voluntary muscle movements.

Pons varoli lies in front of the cerebellum between the midbrain and the medulla oblongata. The nerve fibres in the pons varolii form a bridge between the two cerebellar hemispheres and connect the medulla oblongata with the other region of the brain. The respiratory nuclei found in the pons cooperate with the medulla to control respiration.

Medulla oblongata forms the posterior-most part of the brain. It connects the spinal cord with various parts of the brain. It receives and integrates signals from spinal cord and sends it to the cerebellum and thalamus. Medulla contains vital centres that control cardiovascular reflexes, respiration and gastric secretions.

Question 12.
Differentiate the conditioned stimulus from unconditioned stimulus.
Answer:

Conditioned	Unconditioned
1. Not through learning	Acquired by learning
2. In born reflex	It is not an in born reflex
3. It does not need any past experience	Experience makes it a part of the behaviour
4. Eg: Blinking of an eye when a dust fall in to it.	Eg: Secretion of salivary gland on seeing the food

Question 13.
Tabulate the nerves and functions and its nature of 6-12th cranial nerves.
Answer:

Cranial nerves	Nature of nerve	Function
I Olfactory nerve	Sensory	Sense of smell
II Optic nerve	Sensory	Sense of sight
III Oculomotor nerve	Motor	Movement of the eye
IV Trochlear nerve	Motor	Rotation of the eye ball
V Trigeminal nerve	Sensory and motor (mixed)	Functioning of facial parts
VI Abducens nerve	Motor	Rotation of the eye ball
VII Facial nerve	Mixed	Functioning of facial parts
VIII Auditory/ Vestibulocochlear nerve	Sensory	Maintains the equilibrium of the body/ Auditory function
IX Glossopharyngeal nerve	Mixed	Taste and touch
X Vagus	Mixed	Regulation of the visceral organs
XI Spinal accessory	Motor	Muscular movement of pharynx, larynx, neck and shoulder
XII Hypoglossal	Motor	Speech and swallowing

Question 14.
Tabulate the functions of sympathetic and para sympathetic nerve.
Answer:

Sympathetic nervous system	Para sympathetic nervous system
1. It dialates pupil	It constricts pupil of the eye
2. It inhibits the secretion of saliva	It stimulates saliva secretion
3. It increases the heart beat	It reduces the heart beat
4. It dialates bronches	It constricts the bronchus
5. It inhibits digestion	It stimulates digestion
6. It increases the glucose release	It stimulates bile release
7. Stimulates epinephrine and nor epinephrine release	It reduces the epinephrine and nor epinephrine release
8. Inhibits peristalsis and secretion	Stimulates peristalsis and secretion
9. Reflexes bladder	Contracts bladder

Question 15.
Describe the structure of the cross-section of spinal cord.
Answer:

• There are two indentations the posterior median sulcus and the anterior median fissure.
• In the spinal cord the grey matter forms an inner butterfly-shaped region surrounded by the outer white matter.
• The grey matter consists of dendrites inter neurons and guai cells.
• White matter consists of bundles of nerve fibres.
• Each half of the grey matter is divided into a
• Dorsal horn – Cell bodies of inter neurons.
• Ventral horn – Efferent motor neurons supplying the skeletal muscle.
• Lateral horn – Nerves supply to heart smooth muscles exocrine glands. Originate from the cell bodies.
• Ascending tract – This carry sensory impulses to the brain.
• Descending tract – This carry motor impulses to brain.

Question 16.
Give an account of the functional components of a reflex arc.
Answer:
Sensory receptor – It is a sensory structure that responds to specific stimulus.
Sensory neuron – This neuron takes the sensory impulse to the grey (afferent) matter of the
spinal cord through the dorsal root of the spinal cord.
Inter neuron – It may serve to transmit the impulses from the sensory neuron to the motor neuron.
Motor neuron – It transmits impulse from CNS to the effector organ
Effector neuron – It may be a muscle or gland which responds to the impulse received.

• Lacrymal glands located in the upper lateral region of each orbit secrete tears.
• Tears are secreted at the rate of 1 ml/day.
• Tears contain salt mucus and lysozyme enzyme to destroy bacteria.
• The protective mucus membrane present in the outer surface of the eye ball.
• The eye has two compartments anterior and posterior compartments filled with aqueous humour and vitreous humour respectively.
• The eye ball is consists of three layers sclera, vascular choroid and sensory retina.

Sclera:

• It consists of anterior cornea and the posterior sclera.
• Cornea is composed of stratified squamous epithelium. Sclera forms the white of the eye and protects the eyeball.
• At the junction of the sclera and the cornea is a channel called canal of schlemm which continuously drains out the excess of aqueous humour.

Choroid layer:
It is highly vascularised pigmented layer.

Question 17.
Tabulate the differences between sympathetic and parasympathetic neural system.
Answer:

Sympathetic Neural System (SNS)	Parasympathetic Neural System (PNS)
SNS originates in the thoracic and lumbar region of the spinal cord.	PNS originates in the cranial region of the brain and the sacral region of the spinal cord.
Sympathetic ganglia are linked up to form a chain.	Its ganglia remain isolated
Preganglionic fibres are short and the postganglionic fibres are long.	Preganglionic fibres are long and the postganglionic fibres are short.
Noradrenaline is produced at the terminal ends of the postganglionic fibres at the effector organs. Hence the system is adrenergic.	Acetylcholine is produced at the terminal ends of the postganglionic fibres at the effector organs. Hence the system is cholinergic.
Active during stressful conditions preparing the body to face them.	Active during relaxing times restoring normal activity after a stress.
The overall effect is excitatory and stimulating.	The overall effect is inhibitory.
It is considered as the flight or fight system.	It is considered as “The rest and Digest System” or “The Feed and Breed System”.

Question 18.
Give an account of the peripheral nervous system.
Answer:

• All nervous tissue outside the central nervous system is the peripheral neural system.
• It includes nerves ganglia enteric plexuses and sensory receptors.
• Ganglia are Sinai masses of nervous tissue.
• The neurons of these plexuses help in regulating the digestive system.
• The specialised structure that helps to respond to changes in the environment are called sensory receptor.
• This triggers nerve impulses along the afferent fibres to CNS.
• PNS comprises 12 pairs of cranial nerves and 31 pairs of the spinal nerve.
• The neural retina layer consists of cones and rods.
• The yellow flat spot at the centre of the posterior region of the retina is called macula lutea.
• A small depression present in the centre of the

Question 19.
Explain the Autonomic Neural System?
Answer:
The autonomic neural system is auto-functioning and self-governed. It is a part of the peripheral neural system that innervates smooth muscles, glands, and cardiac muscle. This system controls and coordinates the involuntary activities of various organs. ANS controlling centre is in the hypothalamus.

An autonomic neural system comprises the following components:

1. A preganglionic neuron whose cell body is in the brain or spinal cord; its myelinated axon exits the CNS as part of cranial or spinal nerve and ends in an autonomic ganglion.
2. Autonomic ganglion consists of an axon of preganglionic neurons and cell bodies of the postganglionic neurons.
3. Postganglionic neuron conveys nerve impulses from autonomic ganglia to visceral effector organs.
4. The autonomic neural system consists of the Sympathetic neural system and the Parasympathetic neural system.

Question 20.
Draw the diagram of the cross-section of the eye.
Answer:

Question 21.
Describe the mechanism of vision.
Answer:

• When light enters the eye it gets refracted by the cornea, aqueous humor and lens and it is focused on the retina and excites the rod and cone cells.
• The rods and cones contain the retinal a derivative of vitamin A and the photo pigment opsin.
• Light induces dissociation of retinal from opsin and causes the structural changes in opsin.
• This generates an action potential in the photo receptor cells.
• It is transmitted by the optic nerves to the visual cortex of the brain via the optic nerves for the perception of vision.

Question 22.
List the refractive errors of eye.
Answer:
Myopia

• The affected person cannot see distant objects.
• As the eyeball is elongated or thickened lens the image of distant object is formed in front of the yellow spot.
• This error can be corrected using a concave lens.

Hypermetropia

• Affected person cannot see the nearby objects.
• This is due to a shortened eyeball and thin lens. So the image of closest object is converged behind the retina.
• This defect can be corrected by using convex lens.

Presbyopia

• Due to aging, the lens loses elasticity and the power of accommodation.
• Convex lenses are used to correct this defect.

Astigmatism

• It is due to the rough curvature of the cornea or lens.
• Cylindrical glasses are used to correct this error.

Question 23.
Describe the structure of an ear?
Answer:
Anatomically the ear is divided into three regions external ear middle ear and inner ear.
External ear:

• It consists of pinna external auditory meatus and ear drum.
• The pinna collects the sound waves.
• The external auditory meatus extends up to the tympanic membrane.
• The tympanic membrane is covered with skin outside and with mucus membrane inside.

Middle ear:

• It is an air-filled cavity in the temporal bone.
• The middle ear contains three ossicles malleus incus and stapes.
• The malleus is attached to the tympanic membrane and its head articulates with the incus.
• The stapes is attached to the oval window in the inner ear.
• The Eustachian tube connects the middle ear cavity with the pharynx

Inner ear:-

• It is the fluid-filled cavity consisting of two parts the bony labyrinth and the membranous labyrinths.
• The bony labyrinth consists of three areas, cochlea, vestibule, and semicircular canals.

a Cochlea is a coiled portion consists of 3 chambers namely.

1. Scala vestibule
2. Scala media
3. Scala tympanii.

Scala vestibule and scala tympani are filled with peri lymph.
The scala media is filled with endo lymph.

Question 24.
Describe the structure and functions of organ of cortii.
Answer:

• Organ of corti is a sensory ridge located on the top of the basilar membrane.
• Basilar membrane contains numerous hair cells that are arranged in four rows.
• Protruding from the apical part of each hair cell is hair like structures known as stereocilia.
• On the organ of cortii a stiff gel membrane called tectorial membrane is situated.
• During the conduction of sound wave sterocilia makes contact with tectorial membrane.

Question 25.
Explain the Refractive errors of the eye or defects of the human eye?
Answer:
Myopia (nearsightedness): The affected person can see the nearby objects but not the distant objects. This condition may result due to an elongated eyeball or thickened lens; so that the image of a distant object is formed in front of the yellow spot. This error can be corrected using a concave lens that diverges the entering light rays and focuses them on the retina.

Hypermetropia (long-sightedness): the affected person can see only the distant objects clearly but not the objects nearby. This condition results due to a shortened eyeball and thin lens; so the image of the closest object is converged behind the retina. This defect can be overcome by using a convex lens that converges the entering light rays on the retina.

Presbyopia:
Due to aging, the lens loses elasticity and the power of accommodation. Convex lenses are used to correct this defect. Astigmatism is due to the rough (irregular) curvature of the cornea or lens. Cylindrical glasses are used to correct this error.

Cataract:
Due to the changes in the nature of the protein, the lens becomes opaque. It can be corrected by surgical procedures.

Question 26.
Differentiate the rods from cones.
Answer:

Rods	Cones
1. Helps in seeing in dim light	Colour perception in bright light
2. Contains Rhodopsin pigment	Contains photopsin
3. The protein retinol and vitamins aldehyde combine to form scotoptin called Rhodopsin	The protein opsin and retinol combine to form photopsin.
4. There are 120 million rods are seen on the retina	6-7 million cone cells are seen on the retina
5. Rods are seen richly over the surface of the foveal region.	Cones are richly present on the foveal region.

Question 27.
A man is cheating with his family in this time a house fly sits on his back at once he lifts the hand and strikes the fly. How can he know that? What are the structures involved in this perception?
Answer:

• The skin senses this skin is the largest sense organ.
• All over the skin sensory receptors of pressure heat cold and pain.
• Following are the sensory receptors of the skin.

Tactile Merkel disc

• It is a light touch receptor lying in the deeper layer of the epidermis.
• Hair follicle receptors. These are light-touch receptors lying around the hair follicles.

Meissner’s corpuscles

• These are small light pressure receptors found just beneath the epidermis in the dermal papillae.
• They are numerous in hair less skin areas such as finger tips and soles of the feet.

Pacinian corpuscles

• These are the large egg-shaped receptors found scattered in the dermis.
• It detects different textures temperature hardness and pain.

Ruffini endings
This lie in the dermis responds to continuous pressure Krause end bulbs are thermo receptors that sense temperature.

Question 28.
Give notes on Defects of the ear.
Answer:

• Deafness may be temporary or permanent
• Conductive deafness
• Possible causes
• The blockage of the ear canal with ear wax.
• Rupture of the ear drum.
• Middle ear infection with fluid accumulation,
• Restriction of ossicular movement.
• Sensory-neural deafness
• The defect may be in the organ of cortii or the auditory nerve or in the ascending auditory pathways or auditory cortex.

Question 29.
Give an account of the mechanism of sound?
Answer:

• Sound waves entering the external auditory meatus fall on the tympanic membrane and get vibrated.
• These vibrations are transmitted to the oval window through the three ear ossicles.
• Since the tympani membrane is 17-20 times larger than the oval windows. This pressure exerted on the oval window is about 20 times more than that on the tympanic membrane.
• This pressure causes the round window to alternately bulge outward and inward meanwhile the basilar membrane along with the organ of Corti moves up and down.
• These movements of hair alternately open and close the mechanically gated ion channel causes action potential.
• This is propagated to the brain as a sound sensation through the cochlear nerve.

Question 30.
Explain the sensory function of skin?
Answer:
Skin is the sensory organ of touch and is also the largest sense organ. This sensation conies from millions of microscopic sensory receptors located all over the skin and associated with the general sensations of contact, pressure, heat, cold and pain. Some parts of the body, such as the fingertips have a large number of these receptors, making them more sensitive. Some of the sensory receptors present in the skin are:

• Tactile Merkel disc is a light touch receptor lying in the deeper layer of the epidermis.
• Hair follicle receptors are light-touch receptors lying around the hair follicles.
• Meissner’s corpuscles are small light pressure receptors found just beneath the epidermis in the dermal papillae. They are numerous in hairless skin areas such as fingertips and soles of the feet.
• Pacinian corpuscles are the large egg-shaped receptors found scattered deep in the dermis and monitoring vibration due to pressure. It allows detecting different textures, temperatures, hardness, and pain.
• Ruffini endings which lie in the dermis respond to continuous pressure.
• Krause end bulbs are thermoreceptors that sense temperature.

Question 31.
Describe the structure of the receptor involved with a diagram.
Answer:

• Taste buds are flask-shaped. There are two major types.
• Gustatory epithelial cells or taste cells.
• Basal epithelial cells or repairing cells.
• Long micro villi called gustatory hairs project from the tip of the gustatory cells and extends through a taste pore to the surface of the epithelium.
• Gustatory hairs are tire sensitive portion of the gustatory cells and they have sensory dendrites which send the signal to the brain.
• The basal cells that act as stem cells divide and differentiate into new gustatory cells.

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Chemistry Guide Pdf Chapter 12 Basic Concepts of Organic Reactions Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Chemistry Solutions Chapter 12 Basic Concepts of Organic Reactions

11th Chemistry Guide Basic Concepts of Organic Reactions Text Book Back Questions and Answers

Textbook Evaluation:

I. Choose the best answer:

Question 1.
For the following reactions
(A) CH₃CH₂CH₂Br + KOH → CH₃ – CH = CH₂ + KBr + H₂O

(B) (CH₃)₃CBr + KOH → (CH₃)₃COH + KBr

(C)
Which of the following statement is correct?
a) (A) is elimination, (B) and (C) are substitution
b) (A) is substitution, (B) and (C) are elimination
c) (A) and (B) are elimination and (C) is addition reaction
d) (A) is elimination, (B) is substitution and (C) is addition reaction
Answer:
d) (A) is elimination, (B) is substitution and (C) is addition reaction

Question 2.
What is the hybridisation state of benzyl carbonium ion?
a) sp²
b) spd²
c) sp³
d) sp²d
Answer:
a) sp²

Question 3.
Decreasing order of nucleophilicity is
a) OH^– > NH₂^– > -OCH₃ > RNH₂
b) NH₂^– > OH^– > -OCH3 > RNH₂
c) NH₂^– > CH₃O^– > OH^– > RNH₂
d) CH₃O^– > NH₂^– > OH^– > RNH₂
Answer:
b) NH₂^– > OH^– > -OCH3 > RNH₂

Question 4.
Which of the following species is not electrophilic in nature?
a) Cl⁺
b) BH₃
c) H₃O⁺
d) ⁺NO₂
Answer:
c) H₃O⁺

Question 5.
Homolytic fission of covalent bond leads to the formation of
a) electrophile
b) nucleophile
c) carbocation
d) free radical
Answer:
d) free radical

Question 6.
Hyper conjucation is also known as
a) no bond resonance
b) Baker – nathan effect
c) both (a) and (b)
d) none of these
Answer:
c) both (a) and (b)

Question 7.
Which of the group has highest + I effect?
a) CH₃–
b) CH₃ – CH₂ –
c) (CH₃)₂ – CH-
d) (CH₃)₃ – C –
Answer:
d) (CH₃)₃ – C –

Question 8.
Which of the following species does not exert a resonance effect?
a) C₆H₅OH
b) C₆H₅Cl
c) C₆H₅NH₂
d) C₆H₅NH₃
Answer:
d) C₆H₅NH₃

Question 9.
– I effect is shown by
a) – Cl
b) – Br
c) both (a) and (b)
d) – CH₃
Answer:
c) both (a) and (b)

Question 10.
Which of the following carbocation will be most stable?
a) Ph₃⁺C –
b) CH₃ – ⁺CH₂ –
c) (CH₃)₂ – ⁺CH
d) CH₂ = CH – ⁺CH₂
Answer:
d) CH₂ = CH – ⁺CH₂

Question 11.
Assertion:
Tertiary Carbocations are generally formed more easily than primary Carbocations ions.
Reason:
Hyper conjucation as well as inductive effect due to additional alkyl group stabilize tertiary carbonium ions.
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 12.
Heterolytic fission of C – Br bond results in the formation of
a) free radical
b) Carbanion
c) Carbocation
d) Carbanion and Carbocation
Answer:
d) Carbanion and Carbocation

Question 13.
Which of the following represent a set of nucleophiles?
a) BF₃, H₂O, NH^2-
b) AlCl₃, BF₃, NH₃
c) CN, RCH₂^–, ROH
d) H⁺, RNH₃⁺, :CCl₂
Answer:
c) CN, RCH₂^–, ROH

Question 14.
Which of the following species does not acts as a nucleophile?
a) ROH
b) ROR
c) PCl₃
d) BF₃
Answer:
d) BF₃

Question 15.
The geometrical shape of carbocation is
a) Linear
b) tetrahedral
c) Planar
d) Pyramidal
Answer:
c) Planar

II. Write brief answer to the following questions:

Question 16.
Write short notes on
a) Resonance
b) Hyper Conjugation
Answer:
a) Resonance (or) Mesomeric effect:
The resonance is a chemical phenomenon which is observed in certain organic compounds possessing double bonds at a suitable position. Certain organic compounds can be represented by more than one structure and they differ only in the position of bonding and lone pair of electrons. Such structures are called resonance structures (canonical structures) and this phenomenon is called resonance. This phenomenon is also called mesomerism or mesomeric effect.

For example, the structure of aromatic compounds such as benzene and conjugated systems like 1,3 – butadiene cannot be represented by a single structure, and their, observed properties can be explained on the basis of a resonance hybrid.

In 1,3 butadiene, it is expected that the bond between C¹ – C² and C³ – C⁴ should be shorter than that of C² – C³, but the observed bond lengths are of same. This property cannot be explained by a simple structure in which two n bonds localised between C¹ – C² and C³ – C⁴. Actually, the n electrons are delocalised as shown below.

The resonating structures are called canonical forms and the actual structure lies between these three resonating structures, and is called a resonance hybrid. The resonance hybrid is represented as below.

Similar to the other electron displacement effect, mesomeric effect is also classified into positive mesomeric effect (+M or +R) and negative mesomeric effect (-M or -R) based on the nature of the functional group present adjacent to the multiple bond.

b) Hyper Conjugation:
The delocalisation of electrons of a bond is called as hyperconjugation. It is a special stabilising effect that results due to the interaction of electrons of a σ -bond (usually C – H or C – C) with the adjacent, empty non-bonding p-orbital or an anti¬bonding σ* or π*-orbitals resulting in an extended molecular orbital. Unlike the electromeric effect, hyper conjugation is a permanent effect.

It requires an α-CH group or a lone pair on atom-like N, O adjacent to a π bond (sp² hybrid carbon). It occurs by the overlapping of the σ-bonding orbital or the orbital containing a lone pair with the adjacent π-orbital or p-orbital.

Example:
In propene, the σ -electrons of C-H bond of methyl group can be delocalised into the π -orbital of doubly bonded carbonas represented below.

In the above structure the sigma bond is involved in resonance and breaks in order to supply electrons for delocalization giving rise to 3 new canonical forms. In the contributing canonical structures: (Il), (III) & (IV) of propene, there is no bond between an α-carbon and one of the hydrogen atoms. Hence the hyperconjugation is also known as “no bond resonance” or “Baker Nathan effect”. The structures (II), (III) & (IV) are polar in nature.

Question 17.
What are electrophiles and nucleophiles? Give suitable examples for each.
Answer:
Electrophiles:
Electrophiles are reagents that are attracted towards negative charge or electron-rich center. They are either positively charged ions or electron-deficient neutral molecules.
Example:
CO₂, AlCl₃, BF₃, FeCl₃, NO⁺, NO⁺₂,, etc.

Nucleophiles:
Nucleophiles are reagents that has high affinity for electropositive centers. They possess an atom that has an unshared pair of electrons. They are usually negatively charged ions or electron-rich neutral molecules.
Example.
NH₃, R-NH₂, R-SH, H₂O, R-OH, CN^–. OH^– etc.

Question 18.
Show the heterolysis of covalent bond by using curved arrow notation and complete the following equations. Identify the nucelophile in each case.
i) CH₃ – Br + KOH →
ii) CH₃ – O – CH₃ + HI →
Answer:
(i) CH₃ – Br + KOH →
CH₃ – Br + KQH → CH₃OH + KBr
Nucleophile is : OH^–

ii) CH₃ – O – CH₃ + HI →
H            I
CH₃ – O – CH₃ + HI → CH₃OH + CH₃ I
Nucleophile is : I^–

Question 19.
Explain inductive effect with suitable example.
Answer:
Inductive effect is defined as the change in the polarisation of a covalent bond due to the presence of adjacent bonds, atoms or groups in the molecule. This is a permanent phenomenon.

Let us explain the inductive effect by considering ethane and ethylchloride as examples. The C-C bond in ethane is non polar while the C-C bond in ethyl chloride is polar. We know that chlorine is more electronegative than carbon, and hence it attracts the shared pair of electron between C-Cl in ethyl chloride towards itself. This develops a slight negative charge on chlorine and a slight positive charge on carbon to which chlorine is attached.

To compensate for it, the C₁ draws the shared pair of electrons between itself and C₂ This polarisation effect is called the inductive effect. This effect is greatest for the adjacent bonds, but they also are felt farther away. However, the magnitude of the charge separation decreases rapidly, as we move away from C₂ and is observed maximum for 2 carbons and almost insignificant after 4 bonds from the active group.

It is important to note that the inductive effect does not transfer electrons from one atom to another but the displacement effect is permanent. The inductive effect represents the ability of a particular atom or a group to either withdraw or donate electron density to the attached carbon. Based on this ability the substituents are classified as +I groups and -I groups. Their ability to release or withdraw the electron through sigma covalent bond is called +I effect and -I effect respectively.

Highly electronegative atoms and atoms of groups which are cany a positive charge are electron-withdrawing or-I group.
Example :
-F , -Cl, -COOH, -NO₂ NH₂

Higher the electronegativity of the substituent, greater is the -I effect. The order of the -I effect of some groups are given below.
NH₃ > NO₂ > CN > SO₃H > CHO > CO > COOH > COCl > CONH₂ > F > Cl > Br > I > OH > OR > NH₂ > C₆H₅ > H

Highly electropositive atoms and atoms are groups which carry a negative charge are electron-donating or +1 groups.
Example:
Alkali metals, alkyl groups such as methyl, ethyl, negatively charged groups such as CH₃O^–, C₂H₅O^–, COO^– etc.

The lesser the electronegativity of the elements, the greater is the +1 effect. The relative order of +1 effect of some alkyl groups is given below.
-C(CH₃)₃ > -CH(CH₃)₂ > -CH₂CH₃ > -CH₃

Question 20.
Explain electromeric effect with suitable example.
Answer:
Electromeric is a temporary effect which operates in unsaturated compounds (containing > C = C <, > C = 0, etc…) in the presence of an attacking reagent.
Let us consider two different compounds.
(i) compounds containing carbonyl group ( > C = O)
(ii) unsaturated compounds such as alkenes ( > C = C < )

When a nucleophile approaches the carbonyl compound, the n electrons between C and O is instantaneously shifted to the more electronegative oxygen. This makes the carbon electron-deficient and thus facilitating the formation of a new bond between the incoming nucleophile and the carbonyl carbon atom.

On the other hand when an electrophile such as H⁺ approaches an alkene molecule, the π electrons are instantaneously shifted to the electrophile and a new bond is formed between carbon and hydrogen. This makes the other carbon electron-deficient and hence it acquires a positive charge.

The electrometric effect, is denoted as E effect. Like the inductive effect, the electrometric effect is also classified as + E and – E based on the direction in which the pair of electrons is transferred to form a new bond with the attacking agent.

When the π electron is transferred towards the attacking reagent, it is called + E (positive electrometric) effect.

The addition of H+ to alkene as shown above is an example of +E effect.
When the n electron is transferred away from the attacking reagent, it is called, -E (negative electrometric) effect.

The attack of CN^– on a carbonyl carbon, as shown above, is an example of – E effect.

Question 21.
Give examples for the following types of organic reactions
(i) β – elimination
(ii) Electrophilic substitution
Answer:
(i) β – elimination:
In this reaction two substituents are eliminated from the molecule, and a new C – C double bond is formed between the carbon atoms to which the eliminated atoms/groups are previously attached. Elimination reaction is always accompanied with change in hybridisation.
Example:
n – Propyl bromide on reaction with alcoholic KOH gives propene. In this reaction hydrogen and Br are eliminated.

(ii) Electrophilic substitution:

Here, Y⁺ is an electrophile.
Example :
Nitration of Benzene

11th Chemistry Guide Basic Concepts of Organic Reactions Additional Questions and Answers

I. Choose the best answer:

Question 1.
In organic reactions, the reactant is called ______.
a) intermediate
b) product
c) substrate
d) by product
Answer:
c) substrate

Question 2.
Heterolysis of C – Cl bond produces
a) Two free radicals
b) Two carbonium ions
c) Two carbanions
d) One cation and one anion
Answer:
d) One cation and one anion

Question 3.
Which one of the following is an example for free radical initiators?
(a) Benzoyl peroxide
(b) Benzyl alcohol
(c) Benzyl acetate
(d) Benzaldehyde.
Answer:
(a) Benzoyl peroxide.

Question 4.
Removal of hydride ion from a methane molecule will give a
a) Methyl radical
b) Carbonium ion
c) Carbanion
d) Methyl group
Answer:
b) Carbonium ion

Question 5.
The shape of carbonium ion is
a) Planar
b) Linear
c) Pyramidal
d) Tetrahedral
Answer:
a) Planar

Question 6.
Which of the following is correct order of the stability of carbocations?
(a) ⁺CH₃ > ⁺CH₂ CH₃> ⁺CH(CH₃)₂ > ⁺C(CH₃)₃
(b) ⁺CH₂CH₃ > ⁺CH₃ >⁺ CH(CH₃)₂ > ⁺C(CH₃)₃
(c) ⁺C(CH₃)₃ > ⁺CH(CH₃)₂ >⁺CH₂CH₃^–CH₃
(d) ⁺CH(CH₃)₂ > ⁺CH₃ > ⁺CH₂CH₃ > ⁺C(CH₃)₃
Answer:
(c) ⁺C(CH₃)₃ > ⁺CH(CH₃)₂ >⁺CH₂CH₃^–CH₃

Question 7.
The reaction, (CH₃)₃C – Br -» (CH₃)₃ C⁺ + Br is an example of
a) Homolytic fission
b) Heterolytic fission
c) Cracking
d) All the above
Answer:
b) Heterolytic fission

Question 8.
Which one of the following is not electrophile’?
(a) NH₃
(b) AlCl₃
(c) FeCl₃
(d) R-X
Answer:
(a) NH₃

Question 9.
Which of the following species is paramagnetic
a) A carbaonium ion
b) A free radical
c) A carbanion
d) All of these
Answer:
b) A free radical

Question 10.
Which one of the following are positively charged electrophiles?
(a) CO₂
(b) AlCl₃
(c) BF₃
(d) RX
Answer:
(d) RX

Question 11.
Among the following the true property about
is
a) non – planar
b) C⁺ is sp² – hybridized
c) Electrophile can attack on C⁺
d) Does not undergo hydrolysis
Answer:
b) C⁺ is sp² – hybridized

Question 12.
Which one of the following species has a tendency to show-I effect?
(a) -CH₃
(b) -CH₂-CH₃
(c) -CH(CH₃)₂
(d) -C₆H₅
Answer:
(d) -C₆H₅

Question 13.
Which of the following statements are correct for nucleophile?
a) All negatively charged species are nucleophiles
b) Nucleophiles are Lewis bases
c) Alkenes, alkynes, benzene and pyrrole are nucleophiles
d) All are correct
Answer:
d) All are correct

Question 14.
Which one of the following statement is not correct for electrophile?
a) Electron deficient species are electrophiles
b) Electrophiles are Lewis acids
c) All positively charged species are electrophiles
d) AlCl₃ and SO₃ are electrophiles
Answer:
c) All positively charged species are electrophiles

Question 15.
Electrophiles are
a) Lewis bases
b) Lewis acids
c) Amphoteric
d) All of these
Answer:
b) Lewis acids

Question 16.
Pick out the correct order of acid strength.
(a) CH₃-CH₂-COOH > CH₃COOH > CH₂CICOOH
(b) CH₃COOH > CH₃-CH₂-COOH >CH₂CICOOH
(c) CH₂ClCOOH > CH₃COOH > CH₃-CH₂-COOH
(d) CH₂ClCOOH > CH₃-CH₂-COOH > CH₃COOH
Answer:
(c) CH₂ClCOOH > CH₃COOH > CH₃—CH₂-COOH

Question 17.
Nucleophiles are
a) Electron loving
b) Electron hating
c) Nucleus loving
d) Nucleus hating
Answer:
c) Nucleus loving

Question 18.
Which of the following statement is false about an electrophile?
a) Electron – deficient species
b) An acidic reagent
c) A reagent which attacks an electron-deficient site in a molecule
d) A species which seeks a pair of electrons
Answer:
c) A reagent which attacks an electron-deficient site in a molecule

Question 19.
Which one of the following electrophiles used for nitration of benzene?
(a) \({ Br }^{ \oplus }\)
(b) \({ { NO }_{ 2 }^{ \ominus } }\)
(c) -NH₂
(d) \({ NO }^{ \ominus }\)
Answer:
(b) \({ { NO }_{ 2 }^{ \ominus } }\)

Question 20.
Ammonia molecule is
a) A nucleophile
b) An electron-deficient
c) A electrophile
d) An acid
Answer:
a) A nucleophile

Question 21.
Methyl carbanion is
a) Electrophile
b) Lewis acid
c) Both (a) and (b)
d) Nucleophile
Answer:
d) Nucelophile

Question 22.
Which of the following statements is correct about the inductive effect?
a) Implies the transfer of lone pair of electrons from more electronegative atom to lesser electronegative atom in a molecule.
b) Implies the transfer to lone pair of electrons from lesser electronegative atom to the more electronegative atom in a molecule
c) Increases with increase in distance
d) Implies the atoms ability to cause bond polarization
Answer:
d) Implies the atoms ability to cause bond polarization

Question 23.
The displacement of electrons in a multiple bond in the presence of attacking reagent is called
a) inductive effect
b) electromeric effect
c) resonance
d) Hyper-conjugation
Answer:
b) electromeric effect

Question 24.
The electromeric effect in organic compounds is a
a) Temporary effect
b) Permanent effect
c) Temporary or permanent effect
d) All of the above
Answer:
a) Temporary effect

Question 25.
Which of the following is not the correct condition for resonance?
a) The positions of all the atomic nuclei in the resonating structures may be differ
b) The resonating structures must have the same number of unpaired or paired electrons
c) The molecules exhibiting resonance must be planar in nature
d) The resonating structures must have nearly the same energies
Answer:
a) The positions of all the atomic nuclei in the resonating structures may be differ

Question 26.
Resonance is due to ______.
a) delocalization of sigma electrons
b) migration of H atoms
c) migration of proton
d) delocalization of pi electrons
Answer:
d) delocalization of pi electrons

Question 27.
Resonance in benzene is accompanied by delocalization of n – electrons. Each n electron is attached with
a) 4 carbons
b) 2 carbons
c) 3 carbons
d) 6 carbons
Answer:
d) 6 carbons

Question 28.
Reaction mechanism describes
a) Sequential account of each step describing the details of electron movement
b) energy changes during bond breaking and bond formation
c) kinetics of the reaction
d) all of these
Answer:
d) all of these

Question 29.
Substitution reaction may be
a) Free radical substitution
b) Nucleophilic substitution
c) Electrophilic substitution
d) All are correct
Answer:
d) All are correct

Question 30.
CH₃ – CH₂ – X + KOH_(alc) → CH₂ = CH₂ + KX + H₂O is
a) addition reaction
b) substitution reaction
c) elimination reaction
d) molecular rearrangement
Answer:
c) elimination reaction

Question 31.
CH₄ + Cl₂ CH₃Cl + HCl is an example
for
a) free radical substitution reaction
b) electrophilic substitution reaction
c) nucleophile substitution reaction
d) nueclophilic addition reaction
Answer:
a) free radical substitution reaction

Question 32.
C₆H₆ + 3 Cl₂ C₆H₆Cl
a) free radical substitution reaction
b) electrophilic addition reaction
c) free radical addition reaction
d) nueclophilic addition reaction
Answer:
c) free radical addition reaction

Question 33.
Which one of the following orders is correct regarding the – I effect of the substituents?
a) – NR₂ < – OR > – F
b) -NR₂ > – OR > – F
c) -NR₂ < – OR< – F
d) -NR₂ > – OR < – F
Answer:
c) -NR₂ < – OR< – F

Question 34.
Decreasing – I power of given groups is
(1) -CN
(2) -NO₂
(3) – NH₃⁺
(4) -F
a) 2 > 1 > 4 > 3
b) 2 > 3 > 4 > 1
c) 3 > 2 > 4 > 1
d) 3 > 2 > 1 > 4
Answer:
d) 3 > 2 > 1 > 4

Question 35.
Which of the following belongs to – I group?
a) – C₆H₅
b) – CH₃
c) – CH₂CH₃
d) – C (CH₃)₃
Answer:
a) – C₆H₅

Question 36.
Which of the following functional group shows + R effect?
a) – CHO
b) – NO₂
c) -CN
d) – NR₂
Answer:
d) – NR₂

Question 37.
Hyper conjugation is
a) σ – π conjugation
b) Due to delocalization of σ and π bonds
c) No bond resonance
d) All of these
Answer:
d) All of these

Question 38.
+ R power of the given groups
(1) -O^–
(2) – NH₂
(3) – OH
(4) – NHCOCH₃ in decreasing order is
a) 1 > 2 > 3 > 4
b) 4 > 3 > 2 > 1
c) 1 > 3 > 2 > 4
d) 1 > 4 > 3 > 2
Answer:
a) 1 > 2 > 3 > 4

Question 39.
In pyridine:

Number of conjugated electrons are:
a) 6
b) 8
c) Zero
d) 5
Answer:
a) 6

Question 40.
In hyperconjugation, the atom involved is
a) β – H atom
b) α – H atom
c) γ – H atom
d) All
Answer:
b) α – H atom

Question 41.
Hyper conjugation involves overlap of the following orbtials
a) σ – σ
b) σ – p
c) p – p
d) π – π
Answer:
b) σ – p

Question 42.
+ I effect is shown by
a) – NO₂
b) – Cl
c) – Br
d) – CH₃
Answer:
d) – CH₃

Question 43.
Zero inductive effect is exerted by
a) C₆H₅ –
b) – H
c) CH₃ –
d) – Cl
Answer:
b) – H

Question 44.
Hyper conjugation is most useful for stabilizing which of the following carbocations?
a) neo – Pentyl
b) tert – Butyl
c) iso – Propyl
d) Ethyl
Answer:
b) tert – Butyl

Question 45.
Hyper conjugation phenomenon is possible in
a) H₂C = CH₂
b) CH₃CH₂ – CH = CH₂
c) C₆H₅CH = CH₂
d) (CH₃)₃C – CH = CH₂
Answer:
b) CH₃CH₂ – CH = CH₂

Question 46.
Among the following carbocations which is more stable
a) (C₆H₅)₃C⁺
b)
c)
d)
Answer:
a) (C₆H₅)₃C⁺

Question 47.
The compound which gives the most stable carbonium ion on dehydration
a)
b)
c) CH₃ – CH₂ – CH₂ – CH₂OH
d)
Answer:
b)

Question 48.
Which carbocation is more stable?

Answer:
a)

Question 49.
Arrange the following groups in order of decreasing – R (Or – M) power
(1) NO₂
(2) SO₃H
(3) CF₃
(4) CHO
a) 1 > 3 > 2 > 4
b) 1 > 2 > 3 > 4
c) 1 > 4 > 3 > 2
d)4 > 3 > 2 > 1
Answer:
a) 1 > 3 > 2 > 4

Question 50.
The reaction intermediate produced by homolytic cleavage of bond is called
a) carbocations
b) carbanions
c) free radicals
d) carbenes
Answer:
c) free radicals

Question 51.
Most stable carbocation is
a) CH₃ – ⁺CH₂
b) ⁺CH₂CHCl₂
c) ⁺CH₂CH₂Cl
d) ⁺CH₂ – CH₂NO₂
Answer:
a) CH₃ – ⁺CH₂

Question 52.
Carbocation is a reaction intermediate in which of the following reactions
a) E₁ reactions
b) Electrophilic addition reactions of alkenes and alkynes
c) S_N¹ reactions
d) All of the above
Answer:
d) All of the above

Question 53.
Halogenation of an alkane takes place through the intermediate
a) Carbocation
b) carbanion
c) carbon free radical
d) carbene
Answer:
c) carbon free radical

Question 54.
Which free radical is the most stable?

Answer:
a)

Question 55.
The most stable carbonium ion is
a) Methyl carbonium ion
b) Primary carbonium ion
c) Secondary carbonium ion
d) Tertiary carbonium ion
Answer:
d) Tertiary carbonium ion

Question 56.
Stability of which intermediate is not govern by hyperconjugation?
a) Carbon cation
b) carbon anion
c) carbon-free radical
d) carboniumion
Answer:
b) carbon anion

Question 57.
Which of the following is an electrophilic reagent?
a) H₂O
b) OH^–
c) NO₂⁺
d) All of these
Answer:
c) NO₂⁺

Question 58.
CH₂ = CH₂ + Br₂ → CH₂Br – CH₂Br is an example for
a) addition reaction
b) substitution reaction
c) elimination reaction
d) molecular rearrangement
Answer:
a) addition reaction

Question 59.
R – X + OH^–_(aq) → R – OH + X⁺_(aq) is an example for
a) addition reaction
b) substitution reaction
c) elimination reaction
d) molecular rearrangement
Answer:
b) substitution reaction

Question 60.
C₆H₆ + Cl₂ C₆H₅Cl + HC1 is an example for
a) Free radical substitution reaction
b) Electrophilic substitution reaction
c) Nucleophilic addition reaction
d) Nucelophilic substitution reaction
Answer:
b) Electrophilic substitution reaction

Question 61.
Alkenes readily undergo
a) Substitution reactions
b) Addition reactions
c) Elimination reactions
d) Rearrangement reactions
Answer:
b) Addition reactions

Question 62.
Nitration of benzene is
a) nucleophilic substitution
b) nucleophilic addition
c) electrophilic substitution
d) free radical substitution
Answer:
c) electrophilic substitution

Question 63.
The reaction (CH₃)₃C – Br (CH₃)₃ C – OH is
a) elimination reaction
b) substitution reaction
c) free radical reaction
d) displacement reaction
Answer:
b) substitution reaction

Question 64.
Inductive effect involves
a) displacement of σ – electrons
b) delocalization of π – electrons
c) delocalization of σ – electrons
d) displacement of π – electrons
Answer:
b) delocalization of π – electrons

Question 65.
Compound which shows positive mesomeric effect
a) H₂C = CH – Cl
b) C₆H₅ – NO₂
c) H₂C = CH – CH₂Cl
d) both b & c
Answer:
a) H₂C = CH – Cl

Question 66.
The stability order, in the following carbocations,
CH₃CH₂⁺ (I), (CH₃)₂ ⁺CH (II), (CH₃)₃ C⁺ (III), ⁺CH₃ (IV)
a) I > IV > III > II
b) I > II > III > IV
c) III > IV > I > II
d) III > II > I > IV
Answer:
d) III > II > I > IV

Question 67.
Which is most stable carbocation?
a) n – propyl cation
b) iso – propyl cation
c) Ethyl cation
d) Triphenylmethyl cation
Answer:
d) Triphenylmethyl cation

Question 68.
Which one of the following carbanions is least stable?
a) CH₃CH₂^–
b) HC ≡ C^–
c) (C₆H₅)₃C^–
d) (CH₃)₃C^–
Answer:
d) (CH₃)₃C^–

Question 69.
Among the following, the strongest nucleophile is
a) C₂H₅SH
b) CH₃COO^–
c) CH₃NH₂
d) NCCH₂^–
Answer:
a) C₂H₅SH

Question 70.
Which of the following is least reactive in a nucleophile substitution reaction?
a) (CH₃)₃C – Cl
b) CH₂ = CHCl
c) CH₃CH₂Cl
d) CH₂ = CHCH₂Cl
Answer:
b) CH₂ = CHCl

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

Question 1.
What are organic reactions?
Answer:
The substrate is an organic molecule that reacts with a reagent, which may be an organic, inorganic, or any agent like heat, photon, etc, that brings about the chemical change to form a product, this is known as organic reactions.

Question 2.
What is the Positive Mesomeric effect? Give example.
Answer:
A positive resonance effect occurs, when the electrons move away from substituents attached to the conjugated system. It occurs, if the electron releasing substituents are attached to the conjugated system. In such cases, the attached group has a tendency to release electrons through resonance. These electron releasing groups are usually denoted as +R or +M groups.
Example:
– OH , – SH , – OR , – SR, – NH₂, – O – etc…

Question 3.
Mention the types of fission of a covalent bond?
Answer:
There are three types of fission of a covalent bond. They are,

• Homolytic cleavage
• Heterolytic cleavage

Question 4.
Explain hyper conjugate effect of vinyl chloride molecule.
Answer:
Hyper conjugation effect is also observed when atoms/groups having lone pair of electrons are attached by a single bond, and in conjugation with a π bond. The lone pair of electrons enters into resonance and displaces π electrons resulting in more than one structure.

Question 5.
What are the types of substitution reactions?
Answer:
In this reaction, an atom or a group of atoms attached to a carbon atom is replaced by a new atom or a group of atoms. Based on the nature of the attacking reagent, these reactions can be classified as

• Nucleophilic substitution
• Electrophilic substitution
• Free radical substitution

Question 6.
Explain free radical substitution reaction with the suitable example.
Answer:

Aliphatic electrophilic substitution
A general aliphatic electrophilic substitution is represented as

Question 7.
Explain Nucleophilic Addition reaction with suitable example.
Answer:

Example:
Addition of HCN to acetaldehyde

Question 8.
Explain free radical addition reaction with suitable example.
Answer:
A general free radical addition reaction can be represented as below.


In the above reaction, Benzoyl perioxide acts as an radial initiator. The mechanism involves free radicals.

Question 9.
Write a note on Functional Group inter conversion.
Answer:
Organic synthesis involves functional group inter conversions. A particular functional group can be converted into other functional group by reacting it with suitable reagents. For example, The carboxylic acid group (-COOH) presents in organic acids can be transformed to a variety of other functional group such as – CH₂-OH, – CONH₂, – COCl by treating the acid with LiAlH₄, NH_3, and SOCl₂ respectively.

Question 10.
Differentiate the carbocation and carbanion.
Answer:
Carbocation:

• In a carbocation carbon-bearing positive charge.
• Carbon bearing positive charge has sp2 hybridization.
• It has a planar structure.
• Example: CH₃⁺ (CH₃)₂\({ C }^{ \ominus }\)H, (CH₃)₃C⁺ etc.

Carbanion:

• In a carbanion carbon bearing negative charge.
• Carbon bearing negative charge has sp³ hybridization.
• It has a pyramidal structure.
• Example: CH₃–\({ C }^{ \ominus }\)H₂, CH₃-CHO, (CH₃)₂\({ C }^{ \ominus }\)H etc.

III. Short answer questions (3 Marks):

Question 1.
Explain the hybridization of carbon in carbocation.
Answer:
In a carbocation, the carbon-bearing positive charge is sp² hybridized and hence it has a planar structure. In the reaction involving such a carbocation, the attack of a negatively charged species (nucleophiles) take place on either side of the carbocation as shown below.

Shape of carbocation

The carbanions are generally pyramidal in shape and the lone pair occupies one of the sp3 hybridized orbitais. An alkyl free radical may be either pyramidal or planar.

Shape of carbanion

The shape of Carbon radical

Question 2.
Write three types of electron movement in organic reaction.
Answer:

• lone pair becomes a bonding pair.
• bonding pair becomes a lone pair.
• a bond breaks and becomes another bond.

Type: 1
A lone pair to a bonding pair
Example:

Type: 2
A bonding pair to a lone pair
Example:

Type: 3
A bonding pair to an another bonding pair
Example:

Question 3.
Explain hyper conjugate effect of acrylonitrile.
Answer:
When electronegative atoms or group of atoms are in conjugation with a π – bond,they pull π – electrons from the multiple bond. In case of carbocations, greater the number of alky groups attached to the carbon bearing positive charge, greater is number of the hyper conjucate structure. thus the stability of various carbocations decreases in the order :
3° Carbocation > 2° Carbocation > 1° Carbocation.

Question 4.
What are functional group interconversions?
Answer:
Organic synthesis involves functional group interconversions. A particular functional group can be converted into other functional groups by reacting it with suitable reagents. For example, the carboxylic acid group (-COOH) present in organic acids can be transformed into -COCl by treating the acid with SOCl₂ reagent.

Question 5.
Explain nucleophilc substituion reaction with suitable example.
Answer:
This reaction can be represented as

Here Y^– is the incoming nuclophile or and attacking species and x^– is the leaving group.

Example:
Hydrolysis of alkyl halides by aqueous KOH.
CH₃Br  CH₃OH + Br^–
Aliphatic nucleophilic substitution reactions take place either by S_N¹ or S_N² mechanism.

Question 6.
Explain Electrophilic Addition Reaction with suitable example.
Answer:
A general electrophilic addition reaction can be represented as below.

Example:
Bromination of alkene to give bromo alkane

Question 7.
What are oxidation and reduction reactions? Give suitable example.
Answer:
Many oxidation and reduction reactions of organic compounds fall into one of the four types of reaction that we already discussed but others do not. Most of the oxidation reaction of organic compounds involves gain of oxygen or loss of hydrogen Reduction involves gain of hydrogen and loss of oxygen.
Example:

IV. Long answer questions (5 Marks):

Question 1.
Explain different types of Fission of a covalent bond.
Answer:
All organic molecules contain covalent bonds which are formed by the mutual sharing of electrons between atoms. These covalent bonds break in two different ways, namely homolytic cleavage (symmetrical splitting) and heterolytic cleavage (unsymmetrical splitting). The cleavage of a bond in the substrate is influenced by the nature of the reagent (attacking agent).

Homolytic Cleavage:
Homolytic cleavage is the process in which a covalent bond breaks symmetrically in such way that each of the bonded atoms retains one electron. It is denoted by a half headed arrow (fish hook arrow). This type of cleavage occurs under high temperature or in the presence of UV light in a compound containing non polar covalent bond formed between atoms of similar electronegativity.

In such molecules, the cleavage of bonds results into free radicals. They are short lived and are highly reactive. The type of reagents that promote holmolytic cleavage in substrate are called as free radical initiators. For example Azobisisobutyronitile (AIBN) and peroxides such as benzoyl peroxide are used as free radical initiators in polymerisation reactions.

As a free radical with an unpaired electron is neutral and unstable, it has a tendency to gain an electron to attain stability. Organic reactions involve homolytic fission of C – C bonds to form alkyl free radicals. The stability of alkyl free radicals is in the following order:
C(CH₃)₃ > CH(CH₃)₂ > CH₂CH₃ > CH₃

Heterolytic Cleavage:
Heterolytic cleavage is the process in which a covalent bond breaks unsymmetrically such that one of the bonded atoms retains the bond pair of electrons. It results in the formation of a cation and an anion. Of the two bonded atoms, the most electronegative atom becomes the anion and the other atom becomes the cation. The cleavage is denoted by a curved arrow pointing towards the more electronegative atom.

For example, in tert-butyl bromide, the C – Br bond is polar as bromine is more electronegative than carbon. The bonding electrons of the C – Br bond are attracted more by bromine than carbon. Hence, the C – Br undergoes heterolytic cleavage to form a tert-butyl cation during hydrolysis.

Let us consider the cleavage in a carbon-hydrogen (C-H) bond of aldehydes or ketones We know that the carbon is more electronegative than hydrogen and hence the heterolytic cleavage of C-H bonds results in the formation of carbanion (carbon bears a negative charge). For example in aldol condensation the OH- ion abstracts a a-hydrogen from the aldehyde, which leads to the formation of the below mentioned carbanion.

Question 2.
Explain the acidic nature of carboxylic acid.
Answer:
When a halogen atom is attached to the carbon which is nearer to the carboxylic acid group, its -I effect withdraws the bonded electrons towards itself and makes the ionisation of H easy. The acidity of various chioro acetic acid is in the following order. The strength of the acid increases with increase in the -J effect of the group attached to the carboxyl group.

Trichioro acetic acid > Dichloro acetic acid > Chloro acetic acid > acetic acid.

Similarly, the following order of acidity in the carboxylic acids is due to the +I effect of alkyl group.