STD-6, CHAPTER-3: NATURE OF MATTER, EXERCISE QUESTION ANSWER

A.     FILL IN THE BLANKS.

1.      The Process of grouping objects with similar properties is called ______.

Ans: classification

2.      Anything that occupies _____ and has _______ is called matter.

Ans: space, mass

3.      In the ________ state of matter, the constituent particles have very little hold on one another.

Ans: gaseous

4.      Light does not pass through a blackboard as it is an ______ object.

Ans: opaque

5.      Smell of a perfume reaches us by the process of _______.

Ans: Diffusion

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

 

1.      Air is a man-made material.                                                                                             False

2.      A thin polythene sheet is transparent.                                                                          True

3.      Pebbles float on water.                                                                                                     False

4.      Diffusion is the mixing of the particles of two materials, on their own.                True

5.      Oxygen gas is slightly soluble in water.                                                                         True

 

C.      TICK THE CORRECT OPTION.

1.      The state/states of matter, that have both a fixed shape and a definite volume, is/are –

(a)   Liquids and solids                                      (b)  gas and liquids

(c)    Solids only                                                   (d) liquids only.

      Ans: Solids only

2.      Your book is made up of matter, because it-

(a)   has mass       

(b)   occupies space         

(c)    occupies space and has some mass       

(d)   does not float on water

      Ans: occupies space and has some mass

3.      Which of the following is an opaque material?

(a)   A piece of wood                  

(b)   A plane, thin sheet of glass      

(c)    Pure air          

(d)   Water in a clear glass container

      Ans: a piece of wood

4.      In which of the following cases would diffusion be the fastest?

(a)   Gas in another gas                                      (b)  liquid in another liquid

(c)    A solid in a liquid                                         (d) a gas in a liquid

      Ans: gas in another gas

5.      Which of the following is insoluble in water?

(a)   Mustard oil                                      (b)  sugar

(c)    Carbon dioxide                               (d) common salt

      Ans: Mustard oil

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

1.      Define the following:

(a)   Natural materials

(b)   Transparent materials

Ans: (a) Natural materials: Materials which occur naturally are called as natural materials.

(b) Transparent materials:  Materials that allow light to pass through them, are called transparent materials.

2.      Name any three materials that are, (i) transparent (ii) opaque in nature.

Ans: (i) Three transparent materials are, air, clean water, glass

(ii) Three opaque materials are, wood, wall, metal

3.      Which state of matter (i) can (ii) cannot easily change its shape and volume? Why?

Ans: (i) Gaseous state of matter can easily change its shape and volume because in gases, the particles have very little hold on each other. Therefore, these particles can move far apart from each other.

(ii) Solid state of matter cannot easily change its shape and volume because in solids, the particles are very tightly packed with each other and cannot move.

4.      Why do materials diffuse into each other?

Ans: Materials diffuse into each other due to the free movement of their particles.

5.      Define the term ‘solubility’. How does it change on increasing the temperature of water?

Ans: (i) The maximum amount of a substance, that can be dissolved in a given volume of water is called the solubility of that substance in water.

(ii) Solubility of a solid substance increases on increasing the temperature of water. Solubility of a gaseous substance decreases on increasing the temperature of water.

6.      Name three materials that are (i) soluble (ii) insoluble in water.

Ans: (i) Three soluble materials in water are, sugar, common salt, vinegar.

(ii) Three insoluble materials in water are, wood, mustard oil, helium.

E.      ANSWER THE FOLLOWING QUESTIONS.

1.      Why do solids have a fixed shape and a definite volume?

Ans: In solids, the particles hold each other very tightly. So they are very closely packed with each other and thus cannot move. Hence, solids have a fixed shape and a definite volume.

2.      Briefly describe an activity to show that pure water is a transparent liquid.

Ans: Materials Required

(i) a glass tubmler

(ii) pure water

Procedure

Take an empty glass tumbler. Fill it with pure water. Put a coin inside the tumbler and look into the tumbler.

Observation

We can see the coin in the water filled tumbler.

The above activity shows that pure water is a transparent liquid.

3.      Describe an activity to show that a solid can diffuse slowly into a liquid.

Ans: Materials required

(i) clean water

(ii) gas jar

(iii) crystals of potassium permanganate

Procedure

Take some clean water in a gas jar. Drop a few crystals of potassium permanganate in water.

Observation

We will see that pink colour spread slowly in water.

The above activity shows that a solid can diffuse slowly into a liquid.

4.      What is a ‘saturated solution’? How can one prepare a saturated solution of common salt in water?

Ans: (i) A solution which cannot dissolve more amount of a given substance at a given temperature is called a saturated solution.

(ii) ACTIVITY

Materials required

(a) a glass tumbler

(b) common salt

(c) Water

(d) a tea spoon

Procedure

Take a glass tumbler half filled with water. Add half teaspoon of common salt in it and stir well. Keep on adding common salt in half teaspoon amounts and stir well after every addition.

Observation

After adding a particular amount, we will observe that common salt is no more dissolving in the given volume of water.

By doing this above activity, we can prepare a saturated solution of common salt in water.

5.      Suggest one activity to show the effect of temperature on the solubility of a solid in water.

Ans: Materials Required

(i) Two glass tumblers

(ii) Water

(iii) Sugar (solid)

Procedure

Take equal volume of water in two separate glass tumblers. Heat the water in one of the tumblers. Now, add equal amounts of sugar in two tumblers and stir. Keep on adding measured amounts of sugar in two tumblers till it stops dissolving.

Observation

It will be observed that the amount of sugar dissolved in hot water is more.