JEE Main 2021 · 16 March · morning · Single correct · +4 / −1
The process that involves the removal of sulphur from the ores is :
- (a) Roasting
- (b) Smelting
- (c) Leaching
- (d) Refining
Answer and solution
Answer (a) Roasting
Solution
Chemistry ma’am · 2 steps
Sulphide ore plus air plus heat: the sulphur leaves as SO2 gas. That is roasting.
- Roasting. The sulphide ore is heated strongly in a regular supply of air, below its melting point. Sulphur is oxidised to SO₂ gas, which escapes, and the metal is left behind as its oxide.
2ZnS + 3O₂ →(Δ) 2ZnO + 2SO₂ ↑
Process What it does Roasting heats the ore in excess air; removes S (and As, Sb) as volatile oxides Smelting reduces the oxide to molten metal; the flux removes gangue as slag Leaching dissolves the ore in a suitable solvent and leaves the gangue behind Refining purifies the crude metal after it has been extracted - So. Removal of sulphur from ores is done by roasting, option (a).
The idea to keep. Sulphide ores are roasted, carbonate and hydrated ores are calcined. Both happen before reduction, because a metal oxide is far easier to reduce than a sulphide.
Answer from the NTA final answer key. Solution by PrepWiser.