Explain: (i) Zone refining     (ii) Column chromatography. 

Write down the reactions taking place in different Zones in the blast furnance during the extraction of Iron. 

Write chemical reactions taking place in the extraction of zinc from zinc blende.

Describe a method for refining nickel.

How can you separate alumina from silica in a baxuite ore associated with silica? Give equations, if any.

Giving examples differentiate between 'roasting' and 'calcium'.

68.

How is leaching carried out in case of low grade copper ores?

Name the processes from which chlorine is obtained as a bye-product. What will happen if an aqueous solution of NaCl is subjected to electrolysis?

Outline the principles of refining of metals by the following methods:
(i) Zone refining.
(ii) Electrolytic refining.
(iii) Vapour phase refining.