NCERT Class 9 Science Chapter 2 Solutions Is Matter around Us Pure includes all the topics that have complete descriptions. NCERT Class 9 Science Chapter 2 Solutions Is Matter around Us Pure will help the students of class 9 to understand concepts.
NCERT Class 9 Science
Chapter 2 Solutions Is Matter around Us Pure covers the complete syllabus
and lets you secure a good rank in the exams. NCERT Class 9 Science Chapter
2 Solutions Is Matter around Us Pure will help you to solve homework and
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NCERT Class 9 Science Chapter 2 Solutions
You must go through all the
topics related to NCERT Class 9 Science Chapter 2 Solutions. All the
topics related to NCERT books so students are advised to read the NCERT Science
book thoroughly to understand all topics. Here we are providing solutions of
NCERT textbook Intex question and exercise questions.
Before you study the NCERT
Class 9 Science Chapter 2 Solutions, you must know the topics and subtopic
of Chapter 2 Is Matter around Us Pure of NCERT Science for Class 9.
1. What is A Mixture?
i Types of Mixtures
2. What is A Solution?
i. Concentration of Solution
ii. What is suspension?
iii. What is A Colloidal Solution?
3. Separating the Components of a Mixture
i. How can we obtain coloured component(Dye)
from Blue/Black ink?
ii. How can we separate cream from milk?
iii. How can we separate a mixture of two
Immiscible liquids?
iv. How can we separate a mixture of
salt and ammonium chloride?
v. Is the dye in black ink a single
colour?
vi. How can we separate a mixture of two
miscible liquids?
vii. How can we obtain different gases
from the air?
viii. How can we obtain pure copper
sulphate from an impure sample?
4. Physical and Chemical Changes
5. What are the Types of Pure Substances?
Students of CBSE affiliated schools and, RBSE and other state boards of Rajasthan, Uttar Pradesh, M.P., Gujrat and all other states can download Solutions of Chapter 2 Is Matter around Us Pure of NCERT Science for Class 9 in English medium and Hindi medium in PDF format for free.
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Chapter 2 Is Matter around Us Pure
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Solutions of Chapter 2 Is Matter Around Us Pure of
NCERT Science for Class 9 Intext questions
Chapter
2
Is
Matter Around Us Pure
NCERT TEXTBOOK
Intext Questions
From Page No. 15
Q.1 What is meant by a substance?
Ans. A pure substance consists of only one type of particle.
Q.2 List the points of differences between homogeneous and heterogeneous mixture.
Ans.
Homogeneous mixtures | Heterogeneous mixtures |
1.They have uniform composition throughout the mass | 1.They have different composition and different properties in the different parts of a sample |
2. There is no visible boundary of separation. | 2. There are visible boundaries of separation. |
3.Example-sugar+ water= solution | 3.Example – sugar + sand |
From Page No. 18
Q Differentiate between homogeneous and heterogeneous mixtures with examples.
Ans.
Homogeneous mixtures | Heterogeneous mixtures |
1.They have uniform composition throughout the mass | 1.They have different composition and different properties in the different parts of a sample |
2.There is no visible boundary of separation. | 2.There is visible boundaries of separation. |
3.Example-sugar + water = solution | 3.Example – sugar + sand |
Q.2How are sol, solution, and suspension different from each other?
Ans.
Sol | Solution | Suspension |
It is stable | It is stable. | It is unstable. |
Size of solute particles lies between 10-7cm – 10-5 cm | Size of solute particles is of 10-8cm | Size of solute particles is 10-5cm. |
Sol scatters a beam of light | Solution does not scatter light | Suspension scatters beam of light. |
Solute particles pass through filter paper. | Solute particles easily pass through filter paper. | In suspension, solute particles do not pass through filter paper. |
Q.3 To make a saturated solution, 36g of sodium chloride is dissolved in 100g of water at 293K. Find its concentration at the temperature.
Ans. Given,
Mass of solute (sodium chloride) =36 g
Mass of solvent (water) = 100 g
Mass of solution = Mass of solute + mass of solvent
= 36 g + 100 g
= 136 g
Concentration=`\frac{mass of solute}{mass of solution}\times 100`
`=\frac{36}{136}\times 100=26.47%`
From Page No. 24
Q.1 How will you separate a mixture containing kerosene and petrol (the difference in their boiling points is more than 250C), which are miscible with each other?
Ans. A mixture containing kerosene and petrol which are miscible with each other can be easily separated by the technique of distillation.
Q.2Name the technique to separate:
(i) butter from curd
(ii) salt from seawater
(iii)camphor from salt.
Ans. (i) Centrifugation technique
(ii) By evaporation
(iii).Sublimation technique
Q.3 What type of mixtures is separated by the technique of crystallization?
Ans. Solids in which the impurities are less, or either insoluble or more soluble than the solids in a particular solvent can be separated by crystallization technique. For example -Alum, sea, salt, impure copper sulphate, etc.
From Page No. 24
Q.1Classify the following as chemical or physical changes:
1Cutting of trees.
2.Melting of butter in a pan.
3.Rusting of the almirah.
4.Boiling of water to form steam
5.Passing of electric current, through water and the water breaking down into hydrogen and oxygen gases.
6.Dissolving common salt in water.
7. Making a fruit salad with raw fruits, and
8. Burning of paper and wood.
Ans. Physical change
1. Cutting of trees.
2. Melting of butter in a pan.
3. Boiling of water to form steam.
4. Dissolving common salt in water.
5. Making a fruit salad with raw fruits.
Chemical change
1.Rusting of almirah.
2.Passing of electric current through water and the water breaking down into hydrogen and oxygen gases.
3.Burning of paper and wood.
Q.2Try segregating the things around you as pure substances or mixtures:
Ans. Pure substances:
1. Distilled water
2. Bread
3. Diamond
4. Graphite
5. Sugar
6.Gold
Mixture
1. Ice-cream
2. Steel
3. Paper
4. Talc
5. Kerosene Oil
6. Solder wire
7. Curd
8. Air
NCERT Class 9 Science Chapter 2 Solutions
NCERT EXERCISES
Q.1Which 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 of sodium chloride and ammonium chloride
(c) Small pieces of metal from in the engine oil of a car.
(d) Different pigments from an extract of flower 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.
Ans.
(a) Evaporation
(b) Sublimation
(c) Filtration
(d) Chromatography
(e) Centrifugation
(f) Separating funnel
(g) Filtration
(h)Magnetic Separation
(i) Sieving
Q.2Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve, soluble, insoluble, filtrate, and residue.
Ans. First, a cup of water is taken as a solvent in a saucer pan and heat it... During heating, milk and tea leaves are added to the solvent as solutes. Now we get 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 filtrate, which dissolves in the filtrate. The resulting solution is the required tea.
Q.3Pragya 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.
(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 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 the temperature on the solubility of a salt?
Ans.
(a). At 313k, the mass of potassium dissolved in 100g of water 62g
At 313K, the mass of potassium nitrate dissolved in 50g of water
=`\frac{62g}{100}\times 50g`
(b). On cooling the solution at room temperature the crystals of potassium chloride will be obtained.
(c) Solubility at 293K
(i) Potassium nitrate = 32g per 100g water
(ii) Sodium chloride = 36g per 100g water
(iii) Potassium chloride =35g per 100 of water
(iv) Ammonium chloride =37g per 100g water
(d)This shows that ammonium chloride has the maximum solubility (37g per 100g water) at 293K
(e)With an increase in temperature the solubility increase and when the temperature decreased, the solubility of these salts decreases.
Q.4Explain the following by giving examples:
(a)Saturated solution (b) pure substance
(c) Colloid (d) suspension
Ans.
(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. If more solute added will settle down at the bottom of the container as a precipitate.
Suppose 300g of a solvent can dissolve a maximum of 100g of a particular solute at 250C. Then, the solution obtained by dissolving 100g of that solute in 300g of that solvent at 250C is said to be a saturated solution at 250
(b)Pure Substance: A pure substance is a substance consisting of a single type of particle, i.e., all constituent particles of the substance have the same chemical properties. Example- gold, silver, etc.
(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 the colloid is quite stable. Colloids cannot be separated by the process of filtration. 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 medium. The particles can be seen with naked eyes. It shows the Tyndall effect. The solute particles settle down when the mixture is left undisturbed. It means suspensions are unstable. Suspensions can be separated by the method of filtration. For example, mixtures of chalk powder and water, wheat flour, and water. Example- chalk- water, paints, etc.
Q.5Classify each of the following as a homogeneous or heterogeneous mixture: soda water, wood, air, soil, vinegar, filtered tea.
Ans. Homogeneous mixture: Soda water, air, vinegar, filtered tea.
Heterogeneous mixture: Wood, soil.
Air is a homogeneous mixture of different gases. If some dust or other particles are present, then air becomes a heterogeneous mixture.
Q.6How would you confirm that a colourless liquid given to you is pure water?
Ans Every liquid has a specific boiling point. Pure water has a boiling point of 1000C (373K) at 1 atmospheric pressure. If the given colourless liquid boils at slightly above or below 1000C, then the given liquid is not pure water. It must boil at sharp l000C, Thus by observing the boiling point, and we can confirm whether a given colourless liquid is pure water or not.
Q.7 Which of the following materials fall in the category of a ‘pure substance’?
(a) Ice (b) Milk
(c) Iron (d) Hydrochloric
(e)Calcium oxide (f) Mercury
(g) Brick (h) Wood
(i) Air
Ans. Pure substances –
(a) Ice (b) Iron
(c) Hydrochloric acid (d Calcium oxide
(e) Mercury
Q.8Identify the solutions among the following mixtures:
(a) Soil (b) Seawater
(c) Air (d) Coal
(e) Soda Water
Ans. The following mixtures are solutions –
(b)Sea water (c)Air
(e)Soda water
Q.9 Which of the following will show the ‘Tyndall effect?
(a) Salt solution (b)Milk
(c) Copper sulphate solution (d)Starch solution
Ans. Milk and starch solution will show the ‘Tyndall effect.
Q.10Classify 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 (j) Soap
(k) Methane (l) Carbon Dioxide
(m) Blood
Ans. Elements-
(a) Sodium (b) Sliver
(c) Tin (d)Silicon
Compound-
(f) Calcium Carbonate
Mixture -
(b)Soil (c)Sugar Solution
(h)Coal (i) Air
(j)Soap (m)Blood
Q.11Which of the following are chemical changes?
(a) Growth of a plant (b) Rusting of iron
(c)Mixing of iron filings and sand (d)Cooking of food
(e)Digestion of food (f) Freezing of water
(g)Burning of a candle
Ans. The following changes are chemical changes:
(a) Growth of a plant (b) Rusting of iron
(c) Cooking of food (d) Digestion of food
(e) Burning of candle
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