Name:

(a) Two chemicals used to destroy germs present in water.

(b) Two diseases which spread through impure water.

(c) A chemical used for loading.

(d) Two substances which add taste to water.

(e) Two household methods to get safe drinking water.

Define:

(a) Sterilisation

(b) Sedimentation

(c) Loading

(d) Aeration

Answer in brief:

(a) Why is river water unfit for drinking ?

(b) Why is tap water a mixture ?

(c) What is mineral water?

(d) What is the purpose of adding bleaching powder to water supplied to the town?

(e) How is chemically pure water obtained in the laboratory?

(f) How is water in a swimming pool kept free from germs?

(g) Why is water important for plants and animals?

Name the steps involved in the purification of drinking water supplied in cities and towns.