Matter in our surrounding Worksheet-2

Matter in our surrounding Worksheet-2

11. During evaporation, particles of a liquid change into vapours only:

A. from the surface

B. from the bulk

C. from both surface and bulk

D. neither from surface nor from bulk.

12. Rate of evaporation depends upon :

A. temperature

B. surface area

C. humidity

D. all the options are correct

13. Pressure of air at sea level is :

A. one atmosphere

B. 76 cm

C. 760 mm

D. all the options are correct.

14. When a gas is compressed at constant temperature :

A. the speed of the molecules increase.

B. the collisions among the molecules increase.

C. the speed of the molecules decreases.

D. the collisions among the molecules decrease.

15. During evaporation :

A. the temperature of the liquid falls

B. the temperature of the liquid rises

C. the temperature of the liquid remains unchanged.

D. all statements are wrong.

16. In summer, we prefer wearing :

A. dark nylon clothes                   B. white cotton clothes

C. white silk clothes                     D. dark silk clothes.

17. Solids cannot be compressed because :

A. constituent particles are very closely packed

B. interparticle attractive forces are weak

C. movement of constituent particles is restricted

D. constituent particles diffuse very slowly.

18. The standard room temperature is taken as :

A. 0°C                 B. 273 K             C. 298 K            D. 20°C

19. Which of the following will not undergo sublimation ?

A. Camphor                                   B. Ammonium chloride

C. Iodine                                        D. Sodium chloride

20. The two major gases present in air are :

A. Nitrogen and oxygen

B. Nitrogen and hydrogen

C. Hydrogen and oxygen

D. Nitrogen and carbon dioxide

Answer Key:

11. A

Explanation: Evaporation is a surface phenomenon.

12. D

Explanation: Evaporation depends upon the surface area of liquid as only surface particles change into vapours. Evaporation increases with increase in temperature. More is the humidity less is the evaporation.

13. D

14. B

Explanation: On compressing a gas the volume of gas decreases and hence the collision of gas molecules increases.

15. A

Explanation: During evaporation the particles of the liquid present on the surface of liquid escape and become part of atmosphere. They need some energy to overcome the force of attraction, which they take up from the rest of the particles or molecules of liquid. As a result, their their temperature gets lowered and cooling is caused.

16. B

Explanation: White cotton clothes absorb sweat which when evaporates gives a cooling effect to the body.

17. A

Explanation: Constituent particles are closely packed in solids. Strong intermolecular force of attraction is present in solids.

18. C

Explanation: The standard room temperature is 298 K or 25ºC.

19. D

Explanation: Sodium chloride is ionic solid .There is strong electrostatic force of attraction between the constituents due to which it does not sublime.

20. A

Explanation: Appox. 78% Nitrogen and 20 % oxygen is present in air.