Question

Match list-I with list-II :

List I	List II
(a) Mercury	(i) Vapour Phase Refining
(b) Copper	(ii) Distillation Refining
(c) Silicon	(iii) Electrolytic Refining
(d) Nickel	(iv) Zone Refining

Choose the most appropriate answer from the option given below:
(A) (a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)
(B) (a)-(ii), (b)-(iv), (c)-(iii), (d)-(ii)
(C) (a)-(i), (b)-(iv), (c)-(ii), (d)-(iii)
(D) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)

Answer 1

Hint: Refining is defined as the purification of a substance or a form from its natural state since the natural state of the substance usually occurs as an unusable form. Refining of solids can be done by growing crystals in its aqueous solution whereas for liquids it can be done by the process of distillation.

Complete Step by Step Solution:
Refining is defined as the purification of a substance or a form, from its naturally occurring state.
The various common methods of refining are as follows:
1) Distillation: This method is used for metals that have a low boiling point, the impure metal is evaporated and pure metal is obtained which is known as distillate. Examples are the refining of zinc and mercury.
2) Liquation: This method is specifically used for metals with low melting points. For example : tin, lead, bismuth, etc. The metal to be refined is placed in a sloping reverberatory furnace and heated gently in the presence of carbon monoxide. The metal flows and leaves the impurities called dross.
3) Electrolytic refining- This process of refining is based on electrolysis where impure metal act as an anode and a strip of metal that is in its pure form acts as a cathode. They are placed in an electrolytic bath and current is passed through it. The impurities fall down and pure metals are collected on the cathode. For example, for industrial purposes, copper is mostly purified through this process.
4) Zone refining- This method of refining is done for metals that are required in very pure form. This is done for metals such as silicon and germanium. This is also known as zone melting. It is based on the principle that impurities that are present in the metals are more soluble in the melted state of metal.
5) Vapour phase refining- This method of refining is done for metals that can be turned into volatile compounds and their impurities are not converted during the formation of compounds. This process is used for refining nickel and the process is known as Mond’s process.
6) Van Arkel method- This process of refining is done to convert metal into its volatile unstable compound form, where during the compound formation the impurities are not affected. The compound which is obtained is further decomposed to get pure metal. This is done for the refining of titanium and zirconium.
Hence, option (D) is the correct answer

Note: The metal that is to be purified by the process of refining is called ‘crude metal’. The crude metal is impure in nature and impurities present can be in the form of slag/flux, the oxides of the metals that are not reduced, non-metals, or the presence of foreign metals.