131.

How will you differentiate between:
Concentration and refining

Give a brief account of the following processes as used in extraction of metals:
(a) Smelting
(b) Magnetic separation

What is electro-refining? Explain with one example.

Describe Van Arkel method to obtain metals of high purity.

Explain how, electrolytic refining purifies a metal?

What do you understand by the following terms: (i) Roasting, (ii) Calcination, (iii) Smelting?

Describe mainly with balanced chemical equations.
(a) Copper from copper pyrites by self reduction.
(b) Zinc from zinc blende by carbon reduction.
(c) Silver from silver glance by cyanide process.

(a) How is aluminium extracted from alumina?
(b) Give balanced equations for the extraction of aluminium from bauxite by electrolysis.
(c) What is the function of cryolite in the extraction of Al from Al₂O₃.

Describe the methods used to obtain concentrated ores.

What is meant by the term "chromatography"?