Given below are two statements :
Statement I : In the metallurgy process, sulphide ore is converted to oxide before reduction.
Statement II : Oxide ores in general are easier to reduce.
In the light of the above statements, choose the most appropriate answer from the options given below:

Solution

Chemistry ma’am · 4 steps

Carbon can grab oxygen easily but not sulphur, so we roast the sulphide to an oxide first.

1. Statement I. Sulphide ores are roasted, which means heating them strongly in air. This turns the sulphide into an oxide and releases SO₂. Reduction happens only after this step, so Statement I is correct.

   2ZnS + 3O₂ →(Δ) 2ZnO + 2SO₂ ZnO + C →(Δ) Zn + CO

2. Statement II. To reduce a sulphide with carbon, the carbon would have to form CS₂. That compound has a positive Δ_f G°, so the reaction is not feasible. To reduce an oxide, carbon forms CO or CO₂, which have large negative Δ_f G°. That makes the overall Δ G negative at high temperature, so oxides are easier to reduce and Statement II is correct.
3. Link between them. Statement II is the reason behind Statement I. Because oxides are easier to reduce, sulphides are first converted into oxides.
4. So. Both statements are correct, which is option (a).

The idea to keep. Reduction works when the reducing agent forms a very stable product. CO and CO₂ are very stable, but CS₂ is not, so oxides reduce easily while sulphides must be roasted first.

Answer from the NTA final answer key. Solution by PrepWiser.