Water pollution is caused due to the addition of:

1. domestic sewage
2. pesticides
3. effluents
4. all of the above

One of the methods to control water pollution is:

1. using synthetic detergents
2. passing wastewater through effluent and sewage treatment plants
3. washing clothes and utensils near water bodies
4. using more fertilizers, pesticides, etc.

Conservation of water can be done by :

1. rainwater harvesting
2. planting trees and plants
3. avoiding misuse of water
4. all of the above

Fill in the blanks:

(a) Water is a …………… solvent.

(b) …………… is the purest form of natural water.

(c) Sand and dust are …………… impurities in water.

(d) Sea water has a high concentration of ……………

(e) Water covers nearly …………… of the surface of the earth.

(f) Evaporation of rain water leaves …………… residue.

(g) …………… is the chemical added to water to remove the tiny suspended particles.

(h) A …………… is a uniform mixture of a solute and a solvent.

(i) Ice, water and steam have different physical states but are chemically ……………

(j) Boiling kills most of the …………… in water.

(k) The elements present in the molecules of water are …………… and ……………