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Nickel is refined by heating the impure metal in a stream of CO to form a volatile carbonyl which is then decomposed. This refining method is
AVan Arkel process
Bzone refining
CMond process
Dliquation
Answer & Solution
Correct answer: C. Mond process
1. Impure Ni + 4CO $\rightarrow$ $Ni(CO)_4$ (volatile) at ~350 K, leaving solid impurities behind.
2. Heating the vapour to ~460 K decomposes it: $Ni(CO)_4 \rightarrow Ni + 4CO$, giving pure nickel.
3. This vapour-phase route is the **Mond process**; Van Arkel uses iodine for Ti/Zr.
_Source: Samacheer Kalvi Class 12 Chemistry Vol.1, Unit 1 'Metallurgy', §1.6.5 (Mond process)_
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