Question

In the given flow chart, I, II, III and IV are_______________

A) Electrolysis, Concentration, Roasting, Calcination
B) Concentration, Electrolysis, Calcination, Roasting
C) Calcination, Concentration, Electrolysis, Roasting
D) Concentration, Electrolysis, Roasting, Calcination

Answer 1

To complete the flowchart, recall the steps involved in the process of metallurgy and isolation of the metal from ores. The extraction and isolation of metals from ores involve three major steps:
1.) The concentration of the ore.
2.) Isolation of the metal from its concentrated ore, and
3.) Purification of the metal.

Complete step by step solution:
Metallurgy: The branch of chemistry which deals with the method of extraction of metals from their ores by profitable means.
Steps involved in the extraction and isolation of metals from their ores:
1.)The concentration of Ores: The removal of the unwanted materials or impurities ( e.g., sand and clays etc.) from the ores is known as concentration. It is the first step involved in the metallurgical process.
Therefore, the flowchart is concentration.
2.) Isolation of metal from its concentrated ore: This step involves following two major steps:
(a) Conversion of concentrated ore into oxide form: This is done by calcination and roasting of the concentrated ore.
-Calcination: Calcination is a process in which ore is heated in the absence of air, to expel water from a hydrated or hydroxide ore and oxide or carbon dioxide from a carbonate ore at a temperature below their melting points.
So, III in the flow chart is calcination.
-Roasting: The removal of the excess sulphur contained in sulphide ores in the form of $S{O_2}$ by heating in an excess of air is called roasting.
Therefore, IV in the given flow chart is roasting.
(b) Reduction of the oxide form to metal: The reduction of the metal oxide usually involves heating it with some other substance acting as a reducing agent (C or CO or even other metal).
3.) Purification of the metal: Process of getting pure metals called purification or refining of the metal.
Metals more reactive than carbon or metals of high reactivity are purified by electrolysis method. Therefore, II in the given flow chart will be electrolysis.

Thus, the correct option is B.

Note: A metal extracted by any method is usually contaminated with some impurities. For obtaining metals of high purity, refining is done and it involves several techniques depending upon the differences in properties of the metal and the impurities. Some of them are:
(a)Distillation (b) Liquation (c) Electrolysis (d) Zone refining (e) Vapour phase refining