JEE Main 2021 · 18 March · evening · Single correct · +4 / −1
Match List - I with List - II :
Choose the most appropriate answer from the option given below :
| 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 |
- (a) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)
- (b) (a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)
- (c) (a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)
- (d) (a)-(i), (b)-(iv), (c)-(ii), (d)-(iii)
Answer and solution
Answer (a) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)
Solution
Chemistry ma’am · 2 steps
Pick each refining method from one property of the metal: how it boils, conducts, freezes or bonds with CO.
- Match property to method. Each refining method exploits one physical or chemical property. Find that property for each metal and the match follows.
Metal Property used Method Mercury Low boiling point (about 357 °C), so it vaporises and leaves impurities behind (ii) Distillation Copper Impure Cu as anode, pure Cu strip as cathode, CuSO₄ solution as electrolyte (iii) Electrolytic Silicon Impurities stay dissolved in the melt rather than in the solid, so a moving molten zone sweeps them to one end (iv) Zone refining Nickel Mond process: Ni + 4CO → Ni(CO)₄ at about 330 to 350 K, which decomposes back to pure Ni at about 450 to 470 K (i) Vapour phase - So. The matching is (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i), which is option (a).
The idea to keep. Volatile metals like Hg and Zn are distilled, Cu goes electrolytic, Si, Ge and Ga need zone refining for semiconductor purity, and Ni (Mond) or Zr and Ti (van Arkel) go vapour phase.
Answer from the NTA final answer key. Solution by PrepWiser.