Essential for Life - Air & Water Worksheet-4

Essential for Life - Air & Water Worksheet-4

12. True/False

a.      Graphite is used in making light bulbs and fluorescent tubes.

b.      Air is a mixture of several gases.

c.      The rate of evaporation is faster in winter as compared to summer.

d.      It is very easy to separate soluble impurities from the solution as compared to insoluble impurities.

e.      Boiling the drinking water for 30 seconds can kill the germs and make it germ free.

f.       The rate of evaporation decreases with increase in temperature.

g.      The rate of evaporation remains constant with increase in temperature.

h.      The rate of evaporation increases with increase in temperature.

Miscellaneous Questions:

13. Arrange the following steps of the process of distillation in the correct sequence.

(A) On heating, water changes into steam and the impurities are left behind

(B) When the steam passes through the condenser, it cools down and turns into water again

(C) Impure water is taken in a round-bottom flask and heated

(D) Pure water is collected in a flask

Fill in the blanks:

14. ___ are the substance/s that make/s water unfit for drinking.

Answer Key:

(12)  a. False

b. True

c. False

d. False

e. False

f. False

g. False

h. True

(13)  (C) Impure water is taken in a round-bottom flask and heated

(A) On heating, water changes into steam and the impurities are left behind

(B) When the steam passes through the condenser, it cools down and turns into water again

(D) Pure water is collected in a flask

(14)  impurities/impurity