Question

Consider the following metallurgical processes.
(i) Heating impure metal with CO and distilling the resulting volatile carbonyl (boiling point ${43}^{o}C$) and finally decomposing at ${150}^{o}C$ to ${200}^{o}C$ to get the pure metal.
(ii) Heating the sulphide ore in air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged sulphide.
(iii) Electrolysing the molten electrolyte containing approximately equal amounts of the metal chloride and $CaC{l}_2$ to obtain the metal.
The process used for obtaining sodium, nickel and copper are, respectively:

• A. (i), (ii) and (iii)
• B. (ii), (iii) and (i)
• C. (iii), (i) and (ii)
• D. (ii), (i) and (iii)

Answer 1

Answer: (C)

(iii), (i) and (ii)

In the extraction of nickel -
The impure nickel is reacted with excess carbon monoxide at $50-{60}^{o}C$ to form the gas nickel carbonyl, leaving the impurities as solids.
The mixture of excess carbon monoxide and nickel carbonyl is heated to $220-{250}^{o}C$. On heating, nickel tetracarbonyl decomposes to give nickel.
In the extraction of copper (from sulphide ores)-
Sulphide ore is heated in air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged sulphide.
In extraction of sodium -
Down's process:
Molten sodium chloride (common salt) is electrolyzed. In this process, $CaC{l}_2$ is used to reduce the melting point of the mixture.