KSEEB Solutions for Class 9 Science Chapter 2 Is Matter Around Us Pure

Karnataka Board Class 9 Science Chapter 2 Is Matter Around Us Pure

KSSEB Solutions for Class 9 Science Chapter 2 Intext Questions

Question 1.
What is meant by substance?
Answer:
Substance is a pure form of matter.

Question 2.
List the points of differences -between homogeneous and heterogeneous mixtures.
Answer:

Homogeneous mixture Heterogeneous mixture
1. Uniform composition. Non-uniform composition.
2. The non-detectable boundary between solute and solvent. Boundaries between solute and solvent particles can be detected.
Ex: (1) Sugar in water
(2) Salt in water
Ex: (1) Sand and salt
(2) Sugar and salt.

Question 3.
Differentiate between homogeneous and heterogeneous mixtures with examples.
Answer:

Homogeneous Mixture Heterogeneous Mixture
This mixture has a uniform composition.
Ex: salt in water
This mixture has a non-uniform composition.
Ex: Oil and water

Question 4.
How are sol, solution and suspension different from each other?
Answer:

Sol Solution Suspension
1. Homogeneous  mixture Homogeneous  mixture Heterogeneous  mixture
2.  Particles six less than the size of the solution. Particles size less
than 1 nm.
Particle size can be seemed by the naked eye.

Question 5.
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:
KSSEB Solutions for Class 9 Science Chapter 2 Is Matter Around Us Pure Q 3

Question 6.
How will you separate a mixture containing kerosene and petrol (difference in their boiling points is more than 25° C) which are miscible with each other?
Answer:
To separate a mixture containing kerosene and petrol (difference in their boiling points is more than 25°C), Fractional distillation method is used.

Question 7.
Name the technique to separate

  1. butter from curd
  2. salt from sea-water
  3. camphor from salt.

Answer:

  1. butter from curd: To separate butter from curd, centrifuge machine can be used or It can be separated by milk churner.
  2. salt from seawater: To separate salt from the seawater evaporation method can be used.
  3. Comphor from salt: By sublimation method, we can separate camphor from salt.

Question 8.
What type of mixtures are separated by the technique of crystallization?
Answer:
By crystallisation method, pure solid in the form of crystals can be separated.

Question 9.
Classify the following as chemical or physical changes:

  1. cutting of trees
  2. melting of butter in a pan
  3. rusting of almirah
  4. boiling of water to form steam
  5. the 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.

Answer:

  1. Cutting of trees: Physical change.
  2. melting of butter in a pan: Physical change.
  3. rusting of almirah: chemical change.
  4. boiling of water to form steam: physical change.
  5. passing of electric current, through water and the water breaking down into hydrogen and oxygen gases: chemical change.
  6. dissolving common salt in water: physical change.
  7. making a fruit salad with raw fruits: physical change.
  8. burning of paper and wood: chemical change.

Question 10.
Try segregating the things around you as pure substances of mixtures.
Answer:

Pure substances Mixtures
Gold, distilled water. seawater, minerals, soil.

KSEEB Solutions for Class 9 Science Chapter 2 Textbook Exercises

Question 1.
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 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.
Answer:
a) Evaporation
b) sublimation
c) Filtration
d) Chromatography
e) Centrifuge.
f) By using separating funnel.
g) Filtration.
h) By using magnet
i) By siering
j) By Filtration.

Question 2.
Write the steps you would use for making tea. Use the words, solution, solvent, solute, dissolve, soluble, insoluble, filterate and residue.
Answer:
Steps for preparing tea:

  1. Take water in a vesssel. Here water is solvent.
  2. Add solutes like sugar and tea powder. Sugar dissolves tea powder is insoluble.
  3. While boiling add milk to it.
  4. By filtration, we get tea (filtrate) only leving behind tea powder as residue.

Question 3.
Pragya tested the solubility of three different substances at different temperatures and collected the data as a given below (results are given in the following table, as grams or substance dissolved in 100 grams of water to form a saturated solution)
KSSEB Solutions for Class 9 Science Chapter 2 Is Matter Around Us Pure Q 4
(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 393 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) At temperature 313K to prepare 50 gms of potassium nitrate, we require 319 of potassium nitrate in 100 gms of water.
(b) Pragya observed that As a solution of potassium nitrate cools, it dissolves slowly.
(c)

  1. At temperature 293 K, 32 gm of potassium nitrate dissolves.
  2. At temperature 293K, the solubility of NaCl is 36 gm.
  3. At temperature 293K, the solubility of KCl is 35 gm.
  4. At temperature 293K, the solubility of NH4Cl is 37 gm.

(d) As temperature increases, rate of solubility increases.

Question 4.
Explain the following giving examples:
(a) Saturated solution.
(b) Pure Substance
(c) Colloid
(d) Suspension.
Answer:
(a) Saturated solution: At any particular temperature a solution that has dissolved as much solute as it is capable of dissolving is said to be a saturated solution.
(b) Pure substance: A pure substance consists of a single type of particles.
(c) Colloid: A colloid is a heterogeneous mixture whose size is too small to be individually seen by naked eyes.
(d) Suspension: A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Particles of a suspension are visible to the naked eye.

Question 5.
Classify each of the following as a homogenous or heterogeneous mixture of soda water, wood, air, soil, vinegar, filtered tea.
Answer:
Homogeneous mixture: soda water, air, vinegar, filtered tea, tree.
Heterogeneous mixture: soil.

Question 6.
How would you confirm that a colourless liquid given to you is pure water?
Answer:
Pure water is obtained by fractional distillation. It has only water molecules. By this, we conclude purity of water.

Question 7.
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
(h) Wood
(i) Air
Answer:
Among these substances ice, iron, mercury, and tree are pure substances.

Question 8.
Identify the solutions among the following mixtures.
(a) Soil
(b) Seawater
(c) Air
(d) Coal
(e) Soda water
Answer:
(a) Soil: minerals.
(b) Seawater: salts
(c) Air: Nitrogen, Oxygen, and other gases.
(d) Coal: carbon
(e) Soda water: carbon dioxide.

Question 9.
Which of the following will show the ‘Tyndall effect’?
(a) salt solution
(b) milk
(c) copper sulphate solution
(d) starch solution
Answer:
Milk, copper sulphate, solution, and starch solution shows the ‘Tyndall effect’.

Question 10.
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
(j) Soap
(k) Methane
(l) Carbon dioxide
(m) Blood
Answer:

Metals Compounds Mixtures
Sodium Silver, lead Silicon, Calcium carbonate, Soap, Methane, Carbon dioxide Soil, Air, Sugar, solution, Blood.

Question 11.
Which of the following are chemical changes?
(a) Growth of a plant
(b) Rusting of iron
(c) Mixing of iron filling and sand
(d) Cooking of food
(e) Digestion of food
(f) Freezing of water
(g) Burning of a candle
Answer:
Among these Rusting of iron, cooking of food, Burning of a candle are chemical changes.

KSEEB Class 9 Science Is Matter Around Us Pure Additional Questions and Answers

Question 1.
What is the special name of Alloy?
Answer :
Solid solution

Question 2.
Name the liquid metal.
Answer :
Mercury

Question 3.
What is a compound?
Answer :
A substance composed of two or more elements. Chemically combined with one another in a fixed proportion.

KSEEB Solutions for Class 9 Science

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