(i) Disposable paper cups are more convenient over disposable plastic cups because:

a) Paper cups can decay naturally with the help of decomposers and become harmless after sometime, but plastic cups do not.

b) They do not pollute the environment as they decay fast but plastic cups do pollute the environment because they are non-biodegradable.

c) Plastic cups can cause health effect to the living organisms if consumed by chance. But paper cups are made from organic products, like plants.

(ii) Biodegradable wastes are decomposed by the micro-organisms. By the process of decomposition, mineral elements like C, N, O and P are cycled back into the biosphere. This is done in the form of manure, etc.