Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Tamilnadu State Board New Syllabus Samacheer Kalvi 9th Science Guide Pdf Chapter 10 Matter Around Us Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 9th Science Solutions Chapter 10 Matter Around Us

9th Science Guide Matter Around Us Text Book Back Questions and Answers

I. Choose the correct answer:

Question 1.
The separation of denser particles from lighter particles done by rotation at high speed is called ………………
(a) Filtration
(b) sedimentation
(c) decantation
(d) centrifugation
Answer:
(d) centrifugaton

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 2.
Among the following ……………… is a mixture.
(a) Common Salt
(b) Juice
(c) Carbon dioxide
(d) Pure Silver
Answer:
(b) Juice

Question 3.
When we mix a drop of ink in water we get a . ………………
(a) Heterogeneous Mixture
(b) Compound
(c) Homogeneous Mixture
(d) Suspension
Answer:
(c) Homogeneous Mixture

Question 4.
……………….is essential to perform separation by solvent extraction method.
(a) Separating funnel
(b) filter paper
(c) centrifuge machine
(d) sieve
Answer:
(a) Separating funnel

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 5.
………………… has the same properties throughout the sample.
(a) Pure substance
(b) Mixture
(c) Colloid
(d) Suspension
Answer:
(a) Pure substance

II. State whether true or false. If false, correct the statement.

1. Oil and water are immiscible in each other.
Answer:
True.

2. A compound cannot be broken into simpler substances chemically.
Answer:
False
Correct statement: A compound can be broken into simpler substances chemically.

3. Liquid – liquid colloids are called gels
Answer:
False.
Correct statement: Liquid – solid colloids are called gels.

4. Buttermilk is an example of heterogeneous mixture.
Answer:
True.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

5. Aspirin is composed of 60% Carbon, 4.5% Hydrogen and 35.5% Oxygen by mass. Aspirin is a mixture.
Answer:
False.
Correct statement: It is Compound. It is because the components are combined in a fixed ratio by mass.

III. Match the following :

A B
Element Settles down on standing
compound Impure substance
Colloid Made up of molecules
Suspension Pure substance
Mixture Made up of atoms

Answer:

A B
Element Pure substance
compound Made up of atoms
Colloid Made up of molecules
Suspension Settles down on standing
Mixture Impure substance

IV. Fill in the blanks :

1. A …………………. mixture has no distinguishable boundary between its components.
Answer:
Homogeneous

2. An example of a substance that sublimes is…………
Answer:
Dry ice / Solid CO2 / Camphor

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

3. Alcohol can be separated from water by ………….
Answer:
Fractional distillation

4. In petroleum refining, the method of separation used is ………….
Answer:
Fractional distillation

5. Chromatography is based on the principle of………….
Answer:
different solubilities

V. Very Short answer :

Question 1.
Differentiate between absorption and adsorption.
Answer:
Absorption

  1. Absorption is the process in which the substance is dissolved throughout the bulk of another substance.
  2. For example a paper (absorbent) soaks up or absorbs water.

Adsorption

  1. Adsorption is the process in which particles of a substance, (it could be gas, liquid or dissolved solid) adhere to a surface of another substance.
  2. For example: charcoal adsorbs gases on its surface. Charcoal is called the adsorbent and the gas is called the adsorbate.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 2.
Define Sublimation.
Answer:
Some solids changes directly to vapours on heating. This is called sublimation.

Question 3.
A few drops of ‘DettoP when added to water the mixture turns turbid. Why?
Answer:
The Dettol formulation is a stabilised micro-emulsion. It is manufactured using Chloroxylenol 4.8% and the rest made up by pine oil, isopropanol, castor oil, and soap. On dilution with water, the micro-emulsion destabilises releasing the pine oil and castor oil as a visible bloom. That is why the mixture turns turbid.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 4.
Name the apparatus that you will use to separate the components of mixtures containing two, i. miscible liquids, ii. immiscible liquids.
Answer:
(i) miscible liquids : Distillation flask, fractionating column.
(ii) immiscible liquids : Separating funnel.

Question 5.
Name the components in each of the following mixtures.
i. Ice cream ii. Lemonade iii. Air iv. Soil
Answer:
(i) Ice cream, is a mixture of cream, milk, sugar & sometimes egg.
(ii) Lemonade is a mixture of lemon juice, sugar and water.
(iii) Air is a mixture of nitrogen, oxygen, carbon dioxide, water vapour and other gases.
(iv) Soil is a mixture of clay, sand and various salts.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

VI. Answer briefly :

Question 1.
Which of the following are pure substances? Ice, Milk, Iron, Hydrochloric acid, Mercury, Brick and Water.
Answer:
Ice, Iron, Hydrochloric acid, mercury, brick, water.

Question 2.
Oxygen is very essential for us to live. It forms 21 % of air by volume. Is it an element . or compound?
Answer:
Oxygen is an element.

Question 3.
You have just won a medal made of 22-carat gold. Have you just procured a pure substance or impure substance?
Answer:
lt is a mixture – so it is impure substance.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 4.
How will you separate a mixture containing saw dust, naphthalene and iron filings?
Answer:
The iron filings in the mixture can be separated by Magnetic separation and Naphthalene by sublimation. Saw dust will be remaining at the bottom.

Question 5.
How are homogenous solutions different from heterogeneous solution? Explain with examples.
Answer:
Homogeneous mixtures

  1. Components are uniformly mixed and it will have single phase,
    Eg: Alloys, salt solution, lemonade, petrol etc.
  2. No boundaries of separation between the components. Has single phase.
  3. Components are not visible to naked eye.
  4. They will be in solid, liquid or in the gaseous phase.

Heterogeneous mixtures

  1. Components are not uniformly mixed and it will have more than single phase. They are called suspensions. Eg: chalk in water, petrol in water, sand in water, etc.
  2. There are visible boundaries between the components. Have two or more distinct phases.
  3. Components are visible to naked eye.
  4. Can be a solid-liquid or solid-gas or liquid-gas or solid-solid, or liquid-liquid mixtures.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

VII. Answer in detail:

Question 1.
Write the differences between elements and compounds and give an example for each.
Elements,

  1. Contains only one kind of atoms.
  2. It is a pure substance.
  3. Cannot be broken down further into to simpler substances by chemical methods.
  4. Has definite physical and chemical properties.
  5. Eg., Copper (Cu), Silicon (Si), Gold (Ag)

Compounds

  1. Contains more than one kind of atoms.
  2. It is not a pure substance.
  3. Can be broken down further into simpler substances by chemical methods.
  4. Has definite physical and chemical properties.
  5. Eg., Water (H20), Carbon di oxide (CO2), Ammonia (NH3)

Question 2.
Explain Tyndall effect and Brownian movement with suitable diagram.
Answer:
Brownian Movement:
Brownian movement is a kinetic property. When colloidal solution are viewed under powerful microscope,it can be seen that colloidal particles are moving constantly and rapidly in zig-zag directions.
Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us 1
The Brownian movement of particles is due to the unbalanced bombardment of the particles by the molecules of dispersion medium.

Tyndall effect:

  • Tyndall (1869) observed that when a strong beam of light is focused on a colloidal solution, the path of the beam becomes visible.
  • This phenomenon is known as Tyndall effect and the illuminated path is called Tyndall cone.
  • This phenomenon is not observed in case of true solution.
    Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us 2
  • This phenomenon is due to scattering of light by colloidal particles.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 3.
How is a mixture of common salt, oil and water separated? You can use a combination
of different methods.
Answer:

  • The mixture is taken in a separating funnel., whose mouth is kept closed.
  • Oil and water are immiscible liquids.
  • As common salt can dissolve in water it settles as a separate layer at the bottom of oil layer in the separating funnel.
  • Place a beaker below the funnel to collect salt solution.
  • Open the tap. Allow the salt solution alone to collect in the beaker.
  • From the salt solution, common salt is obtained from evaporation.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us 3

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Intext Activities

ACTIVITY – 1

1. Is air a pure substance or Mixture? Justify
2. You must have seen brass statues in museums and places of worship. Brass is an alloy made up of approx. 30% zinc and 70% copper. Is Brass a pure substance or a mixture or compound?
Answer:
1. Air is a mixture.
Reason : Air contains nitrogen, oxygen, carbon dioxide, dust particles, water
vapour. The composition of air is not the same at all the places.
2. Brass is a mixture of solid in solid.

ACTIVITY – 3

Take some powdered iron filings and mix it with sulphur.
i. Divide the mixture into two equal halves.
ii. Keep the first half of the mixture as it is, but heat the second half of the mixture.
iii. On heating you will get a black brittle compound.
Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us 4
Solution:

  • When Iron fillings and sulphur are mixed both retain their properties it means they have not undergone any chemical reaction.
    Iron + Sulphur → dirty yellow powder
  • When Iron fillings and sulphur are mixed and heated, they undergo a chemical reaction and form Iron sulphide
    Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us 5
  • The black brittle compound is iron sulphate.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

ACTIVITY – 4

Identify whether the given substance is mixture or compound and justify your answer.
1. Sand and water, 2.Sand and iron filings, 3.Concrete, 4. Water and oil, 5. Salad, 6. Water 7. Carbon dioxide, 8. Cement, 9. Alcohol.
Solution :

Substance Mixture/ compound
1. Sand and water Mixture – No chemical alteration of two components.
2. Sand and iron filings Mixture – Sand (silicon and oxygen) is a compound, but sand with iron filings form a mixture.
3. Concrete Mixture – Concrete is a mixture of lime, cement, water, sand and other rocks.
4. Water and oil Mixture – Water is a compound, but when water is mixed with oil, it forms a heterogeneous mixture.
5. Salad Mixture – salad consist of two or more substances mixed together without any chemical bond.
6. Water Compound – (2-H and 1-O) Both combining elements are mixed chemically.
7. Carbon dioxide Compound – (1-C and 2-O) Both combining elements are
mixed chemically.
8. Cement Mixture – Cement is a mixture of many compounds.
9. Alcohol Compound – It is an organic compound in which one
hydroxyl group is bound to a saturated / unsaturated
carbon atom.

ACTIVITY – 5

1. Take bottles containing sugar, starch and wheat flour.
2. Add one tea spoon full of each one to a glass of water and stir well. Leave it aside for about ten minutes.
What do you observe?
Answer:
Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us 6
When one teaspoon full of sugar, starch and wheat flour are added to a glass of water, sugar dissolves in water but wheat flour does not. If we leave it aside for about 10 minutes, wheat flour settles at the bottom

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Test Yourself :

Question 1.
Why whole milk is white?
Answer:
Milk is white because it reflects all wavelengths of visible light. The mixture of reflected colors produces white light. The reason for this is due to the chemical composition of milk and the size of the particles contained within it.

Question 2.
Why ocean is blue?
Answer:
The ocean looks blue because red, orange and yellow (long wavelength light) are absorbed more strongly by water than is blue (short wavelength light). So when white light from the sun enters the ocean, it is mostly the blue that gets returned. Same reason the sky is blue.

Question 3.
Why sun looks yellow when it is really not?
Answer:
Our sun is actually white (mixture of all wavelength of visible spectrum) if we see it from outer space or high-altitude airplanes. Our atmosphere scatters shorter to bigger wavelengths color from sunlight when the white light travels through it. During day, it scatters violet and blue colours leaving yellowish sunlight (the reason why sky is blue and sunlight is yellow). During morning and evening, the sun appears reddish because light rays needs to travel longer distance in atmosphere which causes scattering of yellow light too.

9th Science Guide Matter Around Us Additional Important Questions and Answers

I. Choose the correct answer :

Question 1.
Liquids have
(a) definite volume, definite shape and are not compressible.
(b) definite volume, no definite shape and are highly compressible.
(c) no definite volume, no definite shape and slightly compressible
Answer:
(b) definite volume, no definite shape and slightly compressible

Question 2.
Inter molecular space is maximum in
(a) solids
(b) liquids
(c) gases
(d) all the above
Answer:
(c) gases

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 3.
Air is a/an,
(a) compound
(b) element
(c) Mixture
(d) Molecule
Answer:
(c) Mixture

Question 4.
Which statement is not correct for a mixture
(a) Components retain their properties
(b) Properties of a mixture are different from its components
(c) Components are mixed in any ratio
(d) Components are separated using simple methods
Answer:
(b) Properties of a mixture are different from its components

Question 5.
A homogeneous mixture of two or more substances is called
(a) True solution
(b) Suspension
(c) Colloidal solution
(d) None of the above.
Answer:
(a) True solution

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 6.
A colloidal solution is a
(a) Homogeneous mixture
(b) Heterogeneous mixture in which dissolved particles cannot be seen with naked eyes
(c) Heterogeneous mixture in which dissolved particles can be seen with naked eyes
(d) All the above
Answer:
(b) Heterogeneous mixture in which dissolved particles cannot be seen with naked eyes

Question 7.
Muddy water is an example of
(a) True solution
(b) Suspension
(c) Colloidal solution
(d) No solution
Answer:
(b) Suspension

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 8.
Solution of soap in water is
(a) True solution
(b) Suspension
(c) Colloidal solution
(d) No solution
Answer:
(c) Colloidal solution

Question 9.
Water is a/an
(a) element
(b) Mixture
(c) Molecule
(d) compound
Answer:
(d) compound

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 10.
When two or more elements combine together they form
(a) element
(b) compound
(c) Mixture
(d) Molecule
Answer:
(b) compound

Question 11.
Which of the following will show the “Tyndall Effect”?
(a) Salt solution
(b) Milk & starch solution
(c) Copper sulphate solution
(d) Sugar solution
Answer:
(b) Milk & starch solution

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 12.
Solid is arrangement of particles
(a) close together
(b) far together
(c) far apart
(d) none of these
Answer:
(a) close together

Question 13.
The movement of particles in liquids is …………………..
(a) Vibrate on the spot
(b) around each other
(c) Move quicks in all direction
(d) none of these
Answer:
(b) around each other

Question 14.
Gases change to liquid by the process of . …………………..
(a) Melting
(b) Vapourising
(c) Condensing
(d) Freezing
Answer:
(c) Condensing

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 15.
The physical state of water at 373 K is . …………………..
(a) solid
(b) liquid
(c) vapour
(d) plasma
Answer:
(c) vapour

Question 16.
The constituents that form a mixture are also called . …………………..
(a) Elements
(b) Compounds
(c) Alloys
(d) Components
Answer:
(d) Components

II. True or False? If false, correct the statement:

1. Atoms are the tiny particles which repel each other when they are squeezed very close.
Answer:
True

2. A teabag placed in a cup of hot water will diffuse into the water.
Answer:
True

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

3. Evaporation does form bubbles.
Answer:
False
Correct statement: No does not, only boiling forms bubbles.

4. The energy for the process of sublimation can be derived either from the surrounding or from the heat supplied.
Answer:
True

5. The pressure of gases does not depend on the temperature of the gas and the volume it occupies
Answer:
False
Correct statement: The pressure of gases does depend on the temperature of the gas and the volume it occupies

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

6. Higher the temperature, higher the kinetic energy of particles.
Answer:
True

7. Solids do not flow.
Answer:
True

8. Gases do not diffuse very easily.
Answer:
False.
Correct statement: Gases diffuse very easily.

9. Mixtures are impure substances.
Answer:
True.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

10. Salt solution is an example of heterogeneous mixture.
Answer:
False.
Correct statement: Salt solution is an example of homogeneous mixture.

III. Match the following :

1. (i)

Column A Column B
1. Metal (a) can be compressed easily
2. Metalloid (b) have least density
3.Heating curve (c) Copper, Mercury, Gold, Chromium
4. Gases (d) Boron, Germanium, Silicon, Arsenic
5. Liquids (e) a plot of temperature versus time

Answer:
1) – c, 2) – d, 3) – e, 4) – a, 5) – b

(ii)

Column A Column B
1. Colloidal solution (a) Carbon, Oxygen, Chlorine, Neon
2. Homegeneous (b) C12H22O11
3. Cane sugar (c) dispersed phase, dispersed medium
4. Non-Metals (d) Oil shaken in water
5. Suspensions (e) True solutions

Answer:
1) – c, 2) – e, 3) – b, 4) – a, 5) – d

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

2. Match the following.

Dispersed phase & Medium Examples
1. Solid solid (a) gel
2. Liquid solid (b) emulsion
3. Liquid-liquid (c) solid foam
4. Gas solid (d)alloys

Answer:
1 – d, 2 – a, 3 – b, 4 – c.

3. Match the following.

Dispersed phase & Medium Examples
1. Solid-liquid (a) Aerosol
2. Solid gas (b) Foam
3. Liquid gas (c) Sol
4. Gas liquid (d) Aerosol

Answer:
1 – c, 2 – a, 3 – d, 4 – b.

IV. Fill in the blanks :

1. A substance must absorb …………….. so that it can melt.
Answer:
heat energy

2. Boiling refers to the process by which a substance changes from the liquid to the gaseous state at its …………. point.
Answer:
boiling

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

3. ………………… is used for industrial refrigeration and transporting frozen food.
Answer:
Dry ice

4. ……………….. is the SI unit of temperature
Answer:
Kelvin

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

5. Elements contain the …………………of the same kind
Answer:
atoms

6. When elements are physically mixed they form…………………
Answer:
mixtures

7. A compound has a definite …………………
Answer:
formula

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

8. Mixture of iron filings and salt is a …………………type of mixtures.
Answer:
heterogeneous

9. …………………is the major difference between true solutions, suspensions and colloids.
Answer:
Particle size

10. Phenomenon of Evaporation takes place at the …………………of a liquid.
Answer:
Surface

11. Inverse of sublimation is called …………………
Answer:
deposition

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

12. Expand the LPG …………………
Answer:
Liquefied Petroleum Gas

13. LPG is ………………… gas.
Answer:
inflammable hydrocarbon

14. Compressibility of solids : …………………..
Answer:
can’t be compressed

15. Fluidity of solids : …………….
Answer:
do not flow

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

16. A mixture does not have fixed …………………….
Answer:
boiling point (or) melting point

17. A compound has a fixed ………………….
Answer:
boiling point (or) melting point

18. The mixture of Iron filling and sale is …………………
Answer:
heterogeneous

19. Gas-solid is ……………………
Answer:
Solid foam

20. Examples of foam is ……………
Answer:
Soap lather / Aerated water

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

21. Evaporation is always accompanied by…………..in temperature.
Answer:
decrease / cooling effect

V. Very short answer:

Question 1.
Define ‘matter’.
Answer:
Matter is anything that has mass & occupies space.

Question 2.
What are the three states of matter?
Answer:
Solids, liquids and gases are the three states of matter.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 3.
What is an atom?
Answer:
The smallest unit of an element which may or may not have an independent existence but always take part in a chemical reaction is called atom.

Question 4.
What is a molecule?
Answer:
The smallest unit of a pure substance which always exist independently and can retain physical and chemical properties of that substance is called a molecule.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 5.
Give an example for a molecule.
Answer:
Hydrogen molecule – consists of 2 atoms of hydrogens.

Question 6.
How is matter classified?
Answer:
Matter is classified as pure and impure substances.

Question 7.
How are pure substances classified?
Answer:
Pure substances are classified as elements and compounds.

Question 8.
Give examples for pure substances.
Answer:
Copper, oxygen, hydrogen.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 9.
How are impure substances classified?
Answer:
Impure substances are classified as homogeneous and heterogeneous.

Question 10.
How are elements classified?
Answer:
Elements are classified as metals, non metals and metalloids.

Question 11.
Give examples for metalloids.
Answer:
Boron, silicon, germanium, and arsenic.

Question 12.
Give the chemical formula for cane sugar.
Answer:
C12H22O11

Question 13.
Expand LPG.
Answer:
Liquefied petroleum gas.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 14.
Name the element which is used in toothpaste to strengthen our teeth.
Answer:
Fluorine.

Question 15.
Name the compounds used in fertilizers.
Answer:
Compounds of phosphorus, nitrogen and potassium are used in fertilizers.

Question 16.
Is blood a pure substance?
Answer:
No blood is not a pure substance. It is a mixture of components such as platelets, red and white blood corpuscles and plasma.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 17.
Name the two types of mixtures.
Answer:
Homogeneous and heterogeneous.

Question 18.
Name some substances that sublime.
Answer:
Camphor, Naphthalene, Mothballs.

Question 19.
Name a suitable method used to separate two immiscible liquids.
Answer:
Separating funnel.

Question 20.
Name a method used to separate two miscible liquids.
Answer:
Fractional distillation.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 21.
Name the machine used in the centrifugation process.
Answer:
Centrifuge.

Question 22.
Give an example for liquid in gas.
Answer:
Aerosol.

Question 23.
What is “Brownian motion”?
Answer:
The erratic random movement of microscopic particles in a fluid, as a result of ‘ continuous bombardment from molecules of the surrounding medium was discovered by the scientist Robert Brown and so the movement is called “Brownian motion”

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

VI. Short answer :

Question 1.
What is an element? ’
Answer:
Each element is made up of only one kind of atom. Element are the building block of all materials. Element of any substance cannot be broken down further into simple substance.

Question 2.
What is a compound?
Answer:
When 2 or more elements combine chamically to form a new substance, the new ‘ substance is called a compound. Example : H2O.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 3.
What is a mixture?
Answer:
A mixture is an impure substance which contains 2 or more kinds of elements or ‘ compounds or both physically mixed together in any ratio.

Question 4.
What is LPG?
Answer:
LPG is liquefied petroleum gas. It contains mixture of butane and propane gas.

Question 5.
Distinguish an element and a compound.
Answer:
Element :

  1. Made up of only one kind of atom.
  2. The smallest particle that retains all its properties in the atom cannot be broken down into simpler substances.

Compound :

  1. Made up of more than one kind of atom.
  2. The smallest particle that retains all the properties in the molecule can be broken down into elements by chemical methods.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 6.
Define sublimation.
Answer:
Certain solid substances when heated change directly from solid to gaseous state without attaining liquid state. The vapours when cooled give back the solid substance. This process is known as sublimation.

Question 7.
What is centrifugation?
Answer:
Centrifugation is the process by which fine insoluble solids from a solid liquid mixture can be separated in a machine called centrifuge.

Question 8.
What is solvent extraction?
Answer:
Solvent extraction method is used to separate two immiscible liquids. This method works on the principle of difference in solubility of two immiscible liquids in a suitable solvent.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 9.
What is distillation?
Answer:
Distillation is a process of obtaining pure liquid from a solution. It is actually a combination of evaporation and condensation.

Question 10.
What is fractional distillation?
Answer:
Fractional distillation is used to separate two or more miscible liquids which do not differ much in their boiling points, (less than 25K).

Question 11.
What is chromatography?
Answer:
Chromatography is a separation technique. It is used to separate different components of a mixture based on their different solubilities in the same solvent.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 12.
What is paper chromatography?
Answer:
Paper chromatography is used .to separate the different coloured dyes in a sample. It is based on the principle of different solubility in the solvent which is absorb to different extents by the chromatography paper.

Question 13.
What is a solution?
Answer:
A solution is a homogeneous mixture of two or more substances.

Question 14.
What is a solute?
Answer:
In a solution, the component present in lesser amount by weight is solute.

Question 15.
What is solvent?
Answer:
In a solution, the component present in larger amount by weight is solvent.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 16.
What are Colloidal Solutions?
Answer:
A colloidal solution is a heterogeneous system consisting of the dispersed phase and the
dispersion medium.

Dispersed phase

  1. Component present in smaller proportion
  2. Analogous to solute of a true solution

Dispersion medium

  1. Component present in larger proportion
  2. Analogous to solvent of a true solution

Question 17.
What is Tyndall effect?
Answer:
Tyndall (1869) observed that when a strong beam of light is focused on a colloidal solution the path of the beam becomes visible. This phenomenon is known as Tyndall effect and the illuminated path is called Tyndall cone. This phenomenon is not observed in case of true solution.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 18.
What are the Types of emulsions?
Answer:
The two liquids mixed can form different types of emulsions. For example, oil and water can form an oil in water emulsion, where the oil droplets are dispersed in water, or they can form a water in oil emulsion, with water dispersed in oil.

Question 19.
What are the uses of emulsions?
Answer:
Emulsions find wide applications in food processing, pharmaceuticals, metallurgy and many other important industries.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

VII. Answer in detail :

Question 1.
What are the characteristics of Pure Substances? (or) List out the characteristics of Pure Substances.
Answer:

  • Made up of only one kind of atom or molecule.
  • The ratio of the components of a pure substance is fixed.
  • Have characteristic set of properties. Physical properties like boiling point, melting point, density etc. are
  • fixed. Such properties will vary with the proportions of constituents present in the mixture.
  • Has the same composition throughout i.e it is homogenous in nature

Question 2.
List out the characteristics of Mixtures.
Answer:

  • The constituents of a mixture are loosely held together without any chemical force between the constituents and in such a case the constituents retain their individual properties.
  • A mixture can be prepared by mixing the constituents in any proportion i.e mixtures do not have any fixed amount of its constituents Formation of mixtures does not involve any exchange of energy
  • Mixtures do not have any characteristic set of properties. Physical properties of mixtures like boiling point, melting point etc. are not fixed. Such properties will vary with the proportions of constituents present in the mixture.
  • Components of a mixture can be separated by Physical methods.

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 3.
Tabulate Differences between mixtures and compounds.
Answer:
Mixtures

  1. A mixture can be separated into its constituents by physical processes like filtration, evaporation, sublimation, magnet distillation, solvent extraction.
  2. A mixture retains or shows the properties of its constituents
  3. Energy (in the form of heat light etc.) is neither given out nor absorbed in the preparation of a mixture
  4. The composition or proportion is variable a mixture does not have a definite formula
  5. A mixture does not have fixed boiling point or melting point

Compounds :

  1. A compound cannot be separated into its constituents by physical processes but can be only separated by chemical process
  2. The properties of a compound are entirely different from those of its constituent elements
  3. Energy (in the forth of heat, light etc.) is given out or absorbed during the preparation of a compound
  4. The composition of a compound is fixed. The constituents are present in a fixed ratio by mass. Compound has a definite formula
  5. A compound has a fixed boiling point or melting point

Question 4.
Write the Classification of colloids based on physical state of dispersed phase and dispersion medium.
Answer:
Dispersed phase or the dispersion medium can be a solid, or liquid or gas. There are eight different combinations possible (The combination in which both the dispersed phase and dispersion medium are gases does not exist as gases are completely miscible and can never give rise to a colloidal solution).
Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us 7

Samacheer Kalvi 9th Science Guide Chapter 10 Matter Around Us

Question 5.
Two immiscible liquids are taken in the above funnel for separation.
Which is denser, X or Y? Suggest any one example for X and one for Y. A third liquid Z which is soluble only in Y is added to the mixture and contents in the funnel are shaken well. How many layers will you observe now? How will you separate the three liquids? Boiling point of X is 98°C, that of Y is 43°C and that of Z is 75°C.
Answer:
Boiling point of the 3 liquids are given as
X is 98°C – Which corresponds to water.
Y is 43°C – Which corresponds to oil.
Z is 75°C – Which corresponds to alcohol.
‘Y’ is more denser.
Only two layers are observed. X is separated by separating funnel, Z is separated by distillation method. Y – is in the distillation flask.

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