STD-5: CHAPTER-8- PROPERTIES OF WATER, EXERCISE QUESTION AND ANSWERS

 A.     FILL IN THE BLANKS.

1.      A substance which dissolves completely in a liquid is said to be ________ in it.

Ans: soluble

2.      The substance, that dissolves in a medium to form a solution, is known as the ______.

Ans: solute

3.       Mustard oil is _________ in water.

Ans: insoluble

4.       Aquatic animals breathe the _______ gas dissolved in water.

Ans: oxygen

5.      Change of a liquid into its vapour form is called ________.

Ans: evaporation

6.      Condensation is the process of change of vapours into _______.

Ans: liquid

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

 

1.      Sugar and salt are soluble in water.                                                                                True

2.      Hair oil is insoluble in water.                                                                                            True

3.      Pebbles float on water.                                                                                                      False

4.      Sand sinks in water.                                                                                                            True

5.      Water vapours can be changed into liquid water by heating.                                   False

 

C.      TICK THE CORRECT OPTION.

 

1.      In a solution of sugar and water -

(a)   Water is the solute                

(b)   Sugar is the solvent        

(c)    Both water and sugar are solutes           

(d)   Water is the solvent

      Ans: Water is the solvent

2.      When sand is mixed with water, it-

(a)   Dissolves and floats on water        

(b)   Does not dissolve but floats on water          

(c)    Does not dissolve but sinks in water         

(d)   Dissolves and sinks in water

      Ans: does not dissolve but sinks in water

3.      Wet clothes get dried due to-

(a)   Water cycle       (b) evaporation        (c) respiration       (d) condensation

       Ans: evaporation

4.      Mixture of sugar, salt and lemon juice in water is a-

(a)   solution                (b) solvent

(c)    solute                    (d) floating mixture

      Ans: solution

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

1.      Define a solution.

Ans: When a substance (solute) dissolves completely in any medium (solvent), we get a solution.

2.      What is a solvent?

Ans: The medium, in which the substance (solute) is dissolved, is called a solvent.

3.      Name two substances that are soluble in water.

Ans: Sugar and salt are soluble in water

4.      Name two substances that are insoluble in water.

Ans: Pebbles, saw dust are insoluble in water.

5.      Write the names of four substances that float on water.

Ans: Cork, Butter paper, hair oil, mustard oil float on water.

6.      Name the three forms of water.

Ans: The three forms of water are liquid, solid and vapour form.

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      Give two examples each of:

(a)   Liquids which dissolve in water

(b)   Liquids which are insoluble in water.

(c)    Solids which float on water.

(d)   Solids which sink in water

Ans: a) lemon juice and vinegar are the liquids which dissolve in water.

b) hair oil, kerosene are the liquids which are insoluble in water.

c) cork and saw dust are the solids which float on water.

d) pebbles and coins are the solids which sink in water.

2.      What do we understand by the terms ‘evaporation’ and ‘condensation’?

Ans: i) Change of a liquid into its vapour form is called Evaporation.

ii) Change of vapour form of a substance into its liquid form, on cooling, is called condensation.

3.      How are clouds formed?

Ans: i) Due to evaporation, the water from different water bodies, rises up in the form of water vapour.

ii) As these go very high, they get cooled and condense to form tiny droplets of liquid water.

In this way, clouds are formed.

4.      How does rain water get impure?

Ans: i) Raindrops, when just formed, are the purest form of water.

ii) By the time, rain water reach the surface of the earth, they dissolve many harmful gases present in air and also get dust and smoke mixed up with them.

Thus, it becomes impure.