Question

4. Give scientific reasons.
a. Foam accumulates on a the surface
of 'dal kept for a long time in
summer.
b. Why are naphthalene balls kept with
clothes to be put away.​

Answer 1

• a) In summer, the atmospheric temperature is favourable for microbial growth. Foodstuffs like 'dal' which kept open for a long time favours the growth of microbes. The microbes release various gases as byproduct and these gases form foam on the surface of foodstuffs having more water content.

• b) Naphthalene balls sublime slowly. When they are placed in clothes, they sublime without leaving any residue. Their role is to drive away any kind of insects which could damage the clothes.