(a) What is meant by non-biodegradable waste materials? Give two examples of non-biodegradable wastes.
(b) Which of the following materials are biodegradable? Animal bones, Iron nails, Plastic mugs, Leather belts, Silver foil.
One of the following animals does not use tracheae as the respiratory organs. This animal is : (a) grasshopper (b) prawn (c) mosquito (d) cockroach