Question

(a) Define corrosion. What name is given to the corrosion of iron ?
(b) Name the colour of coating formed on silver and copper articles, when exposed to air ?
(c) List two damages caused by corrosion and suggest how corrosion can be prevented.

Answer 1

(a) Corrosion is a process by which an oxide layer is formed on a metal surface due to oxidation, when the metal is exposed to moist air. The corrosion of iron is called rusting.

(b) Silver on exposure to moist air develops black coating and copper on exposure to moist air develops greenish coating.

(c) Damages caused by corrosion are :
(i) It reduces the strength of the metal.
(ii) It eats up the metal.

Prevention : Corrosion can be prevented by painting, galvanising, alloying, oiling, tinning or greasing.