CHEMISTRY [2 Mark Question Answer]

A saturated solution is a solution in which no more solute can dissolve at a given temperature. A saturated solution becomes unsaturated on heating. An unsaturated solution is a solution in which more of the solute can be dissolved at a given temperature. An unsaturated solution becomes saturated on cooling.

(a) Methods used to remove suspended impurities are :

1. Sedimentation : Water from sources like river or lakes is first fed into a sedimentation tank. After some time, most of the suspended impurities settle down under the effect of gravity and water becomes clear.
2. Loading : It increases the rate of sedimentation by adding chemicals like potash alum. This makes the fine, suspended particles heavier and they settle down at the bottom of the loading tank.
3. Filtration : The water is passed through a filtration tank, which contains layers of fine sand, gravel and charcoal. These layers act as filters. After passing through these, water is absolutely free from suspended impurities.

(b) Removal of germs from water is done by chlorination. The filtered water is sterilized by adding bleaching powder or by passing chlorine gas. Bleaching powder releases chlorine which dissolves in water and kills germs.

Importance of water in daily life :

1. Water is needed for drinking, washing, cooking, bathing, cleaning, etc.
2. It is used to generate electricity in hydroelectric power stations.
3. It is used for irrigating fields and in the manufacture of various products like medicines.
4. Water serves as a means of transportation of goods and people.
5. It is used to extinguish fires.