State whether the following statements are true or false: (a) When a candle burns, both physical and chemical changes take place. (b) Anaerobic bacteria digest animal waste and produce biogas. (c) Ships suffer a lot of damage though they are painted. (d) Stretching of rubber band is not a physical change.

Question

Philoid · Accepted Answer

(a) True

Melting of wax is a physical change while burning of wax is a chemical change.

(b) True

Anaerobic bacteria decompose the animal waste and it produces biogas.

(c) True

The water of the sea contains many salts. The salt water makes the process of rust formation faster. Therefore, ships suffer a lot of damage from rusting though they are painted.

(d) False

Stretching of rubber is a physical change. It just changes its size when we stretch it and comes to actual size when we leave it.