How are the metals like sodium, potassium and calcium obtained. Give equations.

(a) On which factors does purification of metals depend?

(b) Name the methods used for purification.

(c) With a labelled diagram explain electro-refining of a particular metal.

(a) Give the chemical names and formulae of the main ores of

(i) aluminium,

(ii) iron and

(iii) zinc.

(b) Which impurities are present in bauxite?

(c) What is red mud, how is it removed?

Distinguish between electrolytic methods of reduction and refining.