NCERT Solutions for Class 9 Science Chapter 2 Is Matter Around Us Pure
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Page 1
NCERT
SOLUTIONS
CLASS - 9th
aglase .co
SOLUTIONS
CLASS - 9th
aglase .co
Page 2
Book : Science Ncert Solutions | Chapter-2 Science
Class : 9th
Subject : Science
Chapter : 2
Chapter Name : IS MATTER AROUND US PURE?
Q1 What is meant by a substance?
Answer.A pure substance is the one that consists of a single type of particles, i.e., all constituent
particles of the substance have the same chemical nature. Pure substances can be Classi ed as
elements or compounds.
Page : 15 , Block Name : Questions
Q2 List the points of differences between homogeneous and heterogeneous mixtures.
Answer. A homogeneous mixture is a mixture having a uniform composition throughout the mixture.
For example: salt in water, sugar in water, copper sulphate in water A heterogeneous mixture is a
mixture having a non-uniform composition throughout the mixture. For example: sodium chloride
and iron lings, salt and sulphur, oil and water.
Page : 15 , Block Name : Questions
Q1 Differentiate between homogeneous and heterogeneous mixtures with examples.
Answer. A homogeneous mixture is a mixture having a uniform composition throughout the mixture.
For example, mixtures of salt in water, sugar in water, copper sulphate in water, iodine in alcohol,
alloy, and air have uniform compositions throughout the mixtures. On the other hand, a
heterogeneous mixture is a mixture having a non-uniform composition throughout the mixture. For
example, composition of mixtures of sodium chloride and iron lings, salt and sulphur, oil and water,
chalk powder in water, wheat our in water, milk and water are not uniform throughout the mixtures.
Page : 18 , Block Name : Questions
Q2 How are sol, solution and suspension different from each other?
Answer. Sol is a heterogeneous mixture, In this mixture, the solute particles are so small that they
cannot be seen with the naked eye. Also, they seem to be spread uniformly throughout the mixture.
The Tyndall effect is observed in this mixture. For example: milk of magnesia, mud Solution is a
homogeneous mixture. In this mixture, the solute particles dissolve and spread uniformly throughout
the mixture. The Tyndall effect is not observed in this mixture. For example: salt in water, sugar in
water, iodine in alcohol, alloy Suspensions are heterogeneous mixtures. In this mixture, the solute
particles are visible to the naked eye, and remain suspended throughout the bulk of the medium. The
Page 1 of 8 Aglasem Schools
Class : 9th
Subject : Science
Chapter : 2
Chapter Name : IS MATTER AROUND US PURE?
Q1 What is meant by a substance?
Answer.A pure substance is the one that consists of a single type of particles, i.e., all constituent
particles of the substance have the same chemical nature. Pure substances can be Classi ed as
elements or compounds.
Page : 15 , Block Name : Questions
Q2 List the points of differences between homogeneous and heterogeneous mixtures.
Answer. A homogeneous mixture is a mixture having a uniform composition throughout the mixture.
For example: salt in water, sugar in water, copper sulphate in water A heterogeneous mixture is a
mixture having a non-uniform composition throughout the mixture. For example: sodium chloride
and iron lings, salt and sulphur, oil and water.
Page : 15 , Block Name : Questions
Q1 Differentiate between homogeneous and heterogeneous mixtures with examples.
Answer. A homogeneous mixture is a mixture having a uniform composition throughout the mixture.
For example, mixtures of salt in water, sugar in water, copper sulphate in water, iodine in alcohol,
alloy, and air have uniform compositions throughout the mixtures. On the other hand, a
heterogeneous mixture is a mixture having a non-uniform composition throughout the mixture. For
example, composition of mixtures of sodium chloride and iron lings, salt and sulphur, oil and water,
chalk powder in water, wheat our in water, milk and water are not uniform throughout the mixtures.
Page : 18 , Block Name : Questions
Q2 How are sol, solution and suspension different from each other?
Answer. Sol is a heterogeneous mixture, In this mixture, the solute particles are so small that they
cannot be seen with the naked eye. Also, they seem to be spread uniformly throughout the mixture.
The Tyndall effect is observed in this mixture. For example: milk of magnesia, mud Solution is a
homogeneous mixture. In this mixture, the solute particles dissolve and spread uniformly throughout
the mixture. The Tyndall effect is not observed in this mixture. For example: salt in water, sugar in
water, iodine in alcohol, alloy Suspensions are heterogeneous mixtures. In this mixture, the solute
particles are visible to the naked eye, and remain suspended throughout the bulk of the medium. The
Page 1 of 8 Aglasem Schools
Page 3
Book : Science Ncert Solutions | Chapter-2 Science
Tyndall effect is observed in this mixture. For example: chalk powder and water, wheat our and
water.
Page : 18 , Block Name : Questions
Q3 . To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293 K. Find
its concentration at this temperature.
Answer. Mass of solute (sodium chloride) = 36 g (Given)
Mass of solvent (water) = 100 g (Given)
Then, mass of solution = Mass of solute + Mass of solvent
= (36 + 100 )g
= 136 g
Therefore, concentration (mass by mass percentage) of the solution
Mass of solute
= × 100%
Mass of solvent
36
= × 100%
136
= 26.47%
Page : 18 , Block Name : Questions
Q1 How will you separate a mixture containing kerosene and petrol (difference in their boiling points
is more than 25ºC), which are miscible with each other?
Answer. A mixture of two miscible liquids having a difference in their boiling points more than 25°C
can be separated by the method of distillation. Thus, kerosene and petrol can be separated by
distillation.
In this method, the mixture of kerosene and petrol is taken in a distillation ask with a thermometer
tted in it. We also need a beaker, a water condenser, and a Bunsen burner. The apparatus is arranged
as shown in the above gure. Then, the mixture is heated slowly. The thermometer should be watched
simultaneously. Kerosene will vaporize and condense in the water condenser. The condensed kerosene
is collected from the condenser outlet, whereas petrol is left behind in the distillation ask.
Page : 24 , Block Name : Questions
Page 2 of 8 Aglasem Schools
Tyndall effect is observed in this mixture. For example: chalk powder and water, wheat our and
water.
Page : 18 , Block Name : Questions
Q3 . To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293 K. Find
its concentration at this temperature.
Answer. Mass of solute (sodium chloride) = 36 g (Given)
Mass of solvent (water) = 100 g (Given)
Then, mass of solution = Mass of solute + Mass of solvent
= (36 + 100 )g
= 136 g
Therefore, concentration (mass by mass percentage) of the solution
Mass of solute
= × 100%
Mass of solvent
36
= × 100%
136
= 26.47%
Page : 18 , Block Name : Questions
Q1 How will you separate a mixture containing kerosene and petrol (difference in their boiling points
is more than 25ºC), which are miscible with each other?
Answer. A mixture of two miscible liquids having a difference in their boiling points more than 25°C
can be separated by the method of distillation. Thus, kerosene and petrol can be separated by
distillation.
In this method, the mixture of kerosene and petrol is taken in a distillation ask with a thermometer
tted in it. We also need a beaker, a water condenser, and a Bunsen burner. The apparatus is arranged
as shown in the above gure. Then, the mixture is heated slowly. The thermometer should be watched
simultaneously. Kerosene will vaporize and condense in the water condenser. The condensed kerosene
is collected from the condenser outlet, whereas petrol is left behind in the distillation ask.
Page : 24 , Block Name : Questions
Page 2 of 8 Aglasem Schools
Page 4
Book : Science Ncert Solutions | Chapter-2 Science
Q2 Name the technique to separate
(i) butter from curd,
(ii) salt from sea-water,
(iii) camphor from salt.
Answer.(i) Butter can be separated from curd by centrifugation.
(ii) Salt can be separated from sea-water by evaporation.
(iii) Camphor can be separated from salt by sublimation.
Page : 24 , Block Name : Questions
Q3 What type of mixtures are separated by the technique of crystallisation?
Answer. By the technique of crystallization, pure solids are separated from impurities. For example,
salt obtained from sea is separated from impurities; crystals of alum (Phitkari) are separated from
impure samples.
Page : 24 , Block Name : Questions
Q1 Classify the following as chemical or physical changes:
• cutting of trees,
• melting of butter in a pan,
• rusting of almirah,
• boiling of water to form steam,
• passing of electric current, through water and the water breaking down into hydrogen and oxygen
gases,
• dissolving common salt in water,
• making a fruit salad with raw fruits,
• burning of paper and wood.
Answer. Cutting of trees -> Physical change
• Melting of butter in a pan -> Physical change
• Rusting of almirah -> Chemical change
• Boiling of water to form steam -> Physical change
• Passing of electric current through water, and water breaking down into hydrogen and oxygen gas ->
Chemical change
• Dissolving common salt in water -> Physical change
• Making a fruit salad with raw fruits -> Physical change
• Burning of paper and wood -> Chemical change
Page : 24 , Block Name : Questions
Q2 Try segregating the things around you as pure substances or mixtures.
Answer. Pure substance: Water, salt, sugar Mixture: Salt water, soil, wood, air, cold drink, rubber,
sponge, fog, milk, butter, clothes, food.
Page 3 of 8 Aglasem Schools
Q2 Name the technique to separate
(i) butter from curd,
(ii) salt from sea-water,
(iii) camphor from salt.
Answer.(i) Butter can be separated from curd by centrifugation.
(ii) Salt can be separated from sea-water by evaporation.
(iii) Camphor can be separated from salt by sublimation.
Page : 24 , Block Name : Questions
Q3 What type of mixtures are separated by the technique of crystallisation?
Answer. By the technique of crystallization, pure solids are separated from impurities. For example,
salt obtained from sea is separated from impurities; crystals of alum (Phitkari) are separated from
impure samples.
Page : 24 , Block Name : Questions
Q1 Classify the following as chemical or physical changes:
• cutting of trees,
• melting of butter in a pan,
• rusting of almirah,
• boiling of water to form steam,
• passing of electric current, through water and the water breaking down into hydrogen and oxygen
gases,
• dissolving common salt in water,
• making a fruit salad with raw fruits,
• burning of paper and wood.
Answer. Cutting of trees -> Physical change
• Melting of butter in a pan -> Physical change
• Rusting of almirah -> Chemical change
• Boiling of water to form steam -> Physical change
• Passing of electric current through water, and water breaking down into hydrogen and oxygen gas ->
Chemical change
• Dissolving common salt in water -> Physical change
• Making a fruit salad with raw fruits -> Physical change
• Burning of paper and wood -> Chemical change
Page : 24 , Block Name : Questions
Q2 Try segregating the things around you as pure substances or mixtures.
Answer. Pure substance: Water, salt, sugar Mixture: Salt water, soil, wood, air, cold drink, rubber,
sponge, fog, milk, butter, clothes, food.
Page 3 of 8 Aglasem Schools
Page 5
Book : Science Ncert Solutions | Chapter-2 Science
Page : 24 , Block Name : Questions
Q1 Which separation techniques will you apply for the separation of the following?
(a) Sodium chloride from its solution in water.
(b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride.
(c) Small pieces of metal in the engine oil of a car.
(d) Different pigments from an extract of ower petals.
(e) Butter from curd.
(f) Oil from water.
(g) Tea leaves from tea.
(h) Iron pins from sand.
(i) Wheat grains from husk.
(j) Fine mud particles suspended in water
Answer. (a) Sodium chloride from its solution in water -> Evaporation
(b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride -
>Sublimation
(c) Small pieces of metal in the engine oil of a car -> Centrifugation or ltration ordecantation
(d) Different pigments from an extract of ower petals -> Chromatography
(e) Butter from curd -> Centrifugation
(f) Oil from water -> Using separating funnel
(g) Tea leaves from tea -> Filtration
(h) Iron pins from sand -> Magnetic separation
(i) Wheat grains from husk -> Winnowing
(j) Fine mud particles suspended in water -> Centrifugation
Page : 28 , Block Name : Exercise
Q2 Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve,
soluble, insoluble, ltrate and residue.
Answer. First, water is taken as a solvent in a saucer pan. This water (solvent) is allowed to boil.
During heating, milk and tea leaves are added to the solvent as solutes. They form a solution. Then,
the solution is poured through a strainer. The insoluble part of the solution remains on the strainer as
residue. Sugar is added to the ltrate, which dissolves in the ltrate. The resulting solution is the
required tea.
Page : 28 , Block Name : Exercise
Q3 Pragya tested the solubility of three different substances at different temperatures and collected
the data as given below (results are given in the following table, as grams of substance dissolved in
100 grams of water to form a saturated solution).
Page 4 of 8 Aglasem Schools
Page : 24 , Block Name : Questions
Q1 Which separation techniques will you apply for the separation of the following?
(a) Sodium chloride from its solution in water.
(b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride.
(c) Small pieces of metal in the engine oil of a car.
(d) Different pigments from an extract of ower petals.
(e) Butter from curd.
(f) Oil from water.
(g) Tea leaves from tea.
(h) Iron pins from sand.
(i) Wheat grains from husk.
(j) Fine mud particles suspended in water
Answer. (a) Sodium chloride from its solution in water -> Evaporation
(b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride -
>Sublimation
(c) Small pieces of metal in the engine oil of a car -> Centrifugation or ltration ordecantation
(d) Different pigments from an extract of ower petals -> Chromatography
(e) Butter from curd -> Centrifugation
(f) Oil from water -> Using separating funnel
(g) Tea leaves from tea -> Filtration
(h) Iron pins from sand -> Magnetic separation
(i) Wheat grains from husk -> Winnowing
(j) Fine mud particles suspended in water -> Centrifugation
Page : 28 , Block Name : Exercise
Q2 Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve,
soluble, insoluble, ltrate and residue.
Answer. First, water is taken as a solvent in a saucer pan. This water (solvent) is allowed to boil.
During heating, milk and tea leaves are added to the solvent as solutes. They form a solution. Then,
the solution is poured through a strainer. The insoluble part of the solution remains on the strainer as
residue. Sugar is added to the ltrate, which dissolves in the ltrate. The resulting solution is the
required tea.
Page : 28 , Block Name : Exercise
Q3 Pragya tested the solubility of three different substances at different temperatures and collected
the data as given below (results are given in the following table, as grams of substance dissolved in
100 grams of water to form a saturated solution).
Page 4 of 8 Aglasem Schools
Page 6
Book : Science Ncert Solutions | Chapter-2 Science
(a) What mass of potassium nitrate would be needed to produce a saturated solution of potassium
nitrate in 50 grams of water at 313 K?
(b) Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution
to cool at room temperature. What would she observe as the solution cools? Explain.
(c) Find the solubility of each salt at 293 K. Which salt has the highest solubility at this temperature?
(d) What is the effect of change of temperature on the solubility of a salt?
Answer. (a) Mass of KNO to produce a saturated solution of KNOS in 100 grams of
3
water at 313 K = 62 g
Mass of KNO in 50 grams of water at 313 K
3
62.0×50
= = 31.0g
100
(b) Crystals of potassium chloride will be obtained on cooling the saturated
solution.
(c) Solubility of each salt at 293 K is
( i) Potassium nitrate -> 32 g
( ii) Sodium chloride -> 36 g
( iii) Potassium chloride -> 35 g
(iv) Ammonium chloride -> 37 g
On increasing the temperature, solubility of a salt increases.
Q4 Explain the following giving examples.
(a) saturated solution
(b) pure substance
(c) colloid
(d) suspension
Answer. (a) Saturated solution
A saturated solution is a solution in which the maximum amount of solute has been dissolved at a
given temperature. The solution cannot dissolve beyond that amount of solute at that temperature.
Any more solute added will settle down at the bottom of the container as a precipitate. Suppose 500 g
of a solvent can dissolve a maximum of 150 g of a particular solute at 400C. Then, the solution
obtained by dissolving 150 g of that solute in 500 g of that solvent at 300 K is said to be a saturated
solution at 300 K.
Page 5 of 8 Aglasem Schools
(a) What mass of potassium nitrate would be needed to produce a saturated solution of potassium
nitrate in 50 grams of water at 313 K?
(b) Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution
to cool at room temperature. What would she observe as the solution cools? Explain.
(c) Find the solubility of each salt at 293 K. Which salt has the highest solubility at this temperature?
(d) What is the effect of change of temperature on the solubility of a salt?
Answer. (a) Mass of KNO to produce a saturated solution of KNOS in 100 grams of
3
water at 313 K = 62 g
Mass of KNO in 50 grams of water at 313 K
3
62.0×50
= = 31.0g
100
(b) Crystals of potassium chloride will be obtained on cooling the saturated
solution.
(c) Solubility of each salt at 293 K is
( i) Potassium nitrate -> 32 g
( ii) Sodium chloride -> 36 g
( iii) Potassium chloride -> 35 g
(iv) Ammonium chloride -> 37 g
On increasing the temperature, solubility of a salt increases.
Q4 Explain the following giving examples.
(a) saturated solution
(b) pure substance
(c) colloid
(d) suspension
Answer. (a) Saturated solution
A saturated solution is a solution in which the maximum amount of solute has been dissolved at a
given temperature. The solution cannot dissolve beyond that amount of solute at that temperature.
Any more solute added will settle down at the bottom of the container as a precipitate. Suppose 500 g
of a solvent can dissolve a maximum of 150 g of a particular solute at 400C. Then, the solution
obtained by dissolving 150 g of that solute in 500 g of that solvent at 300 K is said to be a saturated
solution at 300 K.
Page 5 of 8 Aglasem Schools
Page 7
Book : Science Ncert Solutions | Chapter-2 Science
(b) Pure substance
A pure substance is a substance consisting of a single type of particles i.e., all constituent particles of
the substance have the same chemical properties. For example, salt, sugar, water are pure substances.
(c) Colloid
A colloid is a heterogeneous mixture. The size of the solutes in this mixture is so small that they
cannot be seen individually with naked eyes, and seems to be distributed uniformly throughout the
mixture. The solute particles do not settle down when the mixture is left undisturbed. This means
that colloids are quite stable. Colloids cannot be separated by the process of ltration. They can be
separated by centrifugation. Colloids show the Tyndall effect. For example, milk, butter, foam, fog,
smoke, clouds.
(d) Suspension
Suspensions are heterogeneous mixtures. The solute particles in this mixture remain suspended
throughout the bulk of the medium. The particles can be seen with naked eyes. Suspension shows the
Tyndall effect. The solute particles settle down when the mixture is left undisturbed. This means that
suspensions are unstable. Suspensions can be separated by the method of ltration. For example,
mixtures of chalk powder and water, wheat our and water.
Page : 29 , Block Name : Exercise
Q5 Classify each of the following as a homogeneous or heterogeneous mixture. soda water, wood, air,
soil, vinegar, ltered tea.
Answer. Homogeneous mixtures: Soda water, air, vinegar
Heterogeneous mixtures: Wood, soil, ltered tea
Page : 29 , Block Name : Exercise
Q6 How would you con rm that a colourless liquid given to you is pure water?
Answer. Every liquid has a characteristic boiling point. Pure water has a boiling point of 100°C (373 K)
at 1 atmospheric pressure. If the given colourless liquid boils at even slightly above or below 100°C,
then the given liquid is not pure water. It must boil at sharp 100°C. Thus, by observing the boiling
point, we can con rm whether a given colourless liquid is pure water or not.
Page : 29 , Block Name : Exercise
Q7 Which of the following materials fall in the category of a “pure substance”?
(a) Ice
(b) Milk
(c) Iron
(d) Hydrochloric acid
(e) Calcium oxide
(f) Mercury
(g) Brick
Page 6 of 8 Aglasem Schools
(b) Pure substance
A pure substance is a substance consisting of a single type of particles i.e., all constituent particles of
the substance have the same chemical properties. For example, salt, sugar, water are pure substances.
(c) Colloid
A colloid is a heterogeneous mixture. The size of the solutes in this mixture is so small that they
cannot be seen individually with naked eyes, and seems to be distributed uniformly throughout the
mixture. The solute particles do not settle down when the mixture is left undisturbed. This means
that colloids are quite stable. Colloids cannot be separated by the process of ltration. They can be
separated by centrifugation. Colloids show the Tyndall effect. For example, milk, butter, foam, fog,
smoke, clouds.
(d) Suspension
Suspensions are heterogeneous mixtures. The solute particles in this mixture remain suspended
throughout the bulk of the medium. The particles can be seen with naked eyes. Suspension shows the
Tyndall effect. The solute particles settle down when the mixture is left undisturbed. This means that
suspensions are unstable. Suspensions can be separated by the method of ltration. For example,
mixtures of chalk powder and water, wheat our and water.
Page : 29 , Block Name : Exercise
Q5 Classify each of the following as a homogeneous or heterogeneous mixture. soda water, wood, air,
soil, vinegar, ltered tea.
Answer. Homogeneous mixtures: Soda water, air, vinegar
Heterogeneous mixtures: Wood, soil, ltered tea
Page : 29 , Block Name : Exercise
Q6 How would you con rm that a colourless liquid given to you is pure water?
Answer. Every liquid has a characteristic boiling point. Pure water has a boiling point of 100°C (373 K)
at 1 atmospheric pressure. If the given colourless liquid boils at even slightly above or below 100°C,
then the given liquid is not pure water. It must boil at sharp 100°C. Thus, by observing the boiling
point, we can con rm whether a given colourless liquid is pure water or not.
Page : 29 , Block Name : Exercise
Q7 Which of the following materials fall in the category of a “pure substance”?
(a) Ice
(b) Milk
(c) Iron
(d) Hydrochloric acid
(e) Calcium oxide
(f) Mercury
(g) Brick
Page 6 of 8 Aglasem Schools
Page 8
Book : Science Ncert Solutions | Chapter-2 Science
(h) Wood
(i) Air.
Answer. The following materials fall in the category of a "pure substance":
(a) Ice
(c) Iron
(d) Hydrochloric acid
(e) Calcium oxide
(f) Mercury
Page : 29 , Block Name : Exercise
Q8 Identify the solutions among the following mixtures.
(a) Soil
(b) Sea water
(c) Air
(d) Coal
(e) Soda water
Answer. The following mixtures are solutions:
(b) Sea water
(c) Air
(e) Soda water
Page : 29 , Block Name : Exercise
Q9 Which of the following will show “Tyndall effect”?
(a) Salt solution
(b) Milk
(c) Copper sulphate solution
(d) Starch solution.
Answer. Milk and starch solution will show the "Tyndall effect".
Page : 29 , Block Name : Exercise
Q10 Classify the following into elements, compounds and mixtures.
(a) Sodium
(b) Soil
(c) Sugar solution
(d) Silver
(e) Calcium carbonate
(f) Tin
(g) Silicon
(h) Coal
(i) Air
Page 7 of 8 Aglasem Schools
(h) Wood
(i) Air.
Answer. The following materials fall in the category of a "pure substance":
(a) Ice
(c) Iron
(d) Hydrochloric acid
(e) Calcium oxide
(f) Mercury
Page : 29 , Block Name : Exercise
Q8 Identify the solutions among the following mixtures.
(a) Soil
(b) Sea water
(c) Air
(d) Coal
(e) Soda water
Answer. The following mixtures are solutions:
(b) Sea water
(c) Air
(e) Soda water
Page : 29 , Block Name : Exercise
Q9 Which of the following will show “Tyndall effect”?
(a) Salt solution
(b) Milk
(c) Copper sulphate solution
(d) Starch solution.
Answer. Milk and starch solution will show the "Tyndall effect".
Page : 29 , Block Name : Exercise
Q10 Classify the following into elements, compounds and mixtures.
(a) Sodium
(b) Soil
(c) Sugar solution
(d) Silver
(e) Calcium carbonate
(f) Tin
(g) Silicon
(h) Coal
(i) Air
Page 7 of 8 Aglasem Schools
Page 9
Book : Science Ncert Solutions | Chapter-2 Science
(j) Soap
(k) Methane
(l) Carbon dioxide
(m) Blood
Answer. Elements:
(a) Sodium
(d) Silver
(f) Tin
(g) Silicon
(e) Calcium carbonate
(k) Methane
(l) Carbon dioxide
Mixtures
(b) Soil
(c) Sugar solution
(h) Coal
(i) Air
(j) Soap
(m) Blood
Page : 29 , Block Name : Exercise
Q11 Which of the following are chemical changes?
(a) Growth of a plant
(b) Rusting of iron
(c) Mixing of iron lings and sand
(d) Cooking of food
(e) Digestion of food
(f) Freezing of water
(g) Burning of a candle.
Answer. The following changes are chemical changes:
(a) Growth of a plant
(b) Rusting of iron
(d) Cooking of food
(e) Digestion of food
(g) Burning of candle
Page : 30 , Block Name : Exercise
Page 8 of 8 Aglasem Schools
(j) Soap
(k) Methane
(l) Carbon dioxide
(m) Blood
Answer. Elements:
(a) Sodium
(d) Silver
(f) Tin
(g) Silicon
(e) Calcium carbonate
(k) Methane
(l) Carbon dioxide
Mixtures
(b) Soil
(c) Sugar solution
(h) Coal
(i) Air
(j) Soap
(m) Blood
Page : 29 , Block Name : Exercise
Q11 Which of the following are chemical changes?
(a) Growth of a plant
(b) Rusting of iron
(c) Mixing of iron lings and sand
(d) Cooking of food
(e) Digestion of food
(f) Freezing of water
(g) Burning of a candle.
Answer. The following changes are chemical changes:
(a) Growth of a plant
(b) Rusting of iron
(d) Cooking of food
(e) Digestion of food
(g) Burning of candle
Page : 30 , Block Name : Exercise
Page 8 of 8 Aglasem Schools
Document Details
| Board / Org | NCERT |
| Exam | Class 9 |
| Type | Solution |
| Pages | 9 |
| Updated | 30 Apr 2026 |