Chemistry - Metallurgy Question with Solution | TestHub

(A) Self-reduction

Metal sulfide reduces its own oxide, which is called self-reduction / auto-reduction.

(B) Excess O₂ needed in step-2

Step-2 is a redox internal reaction, not oxidation by oxygen.

So, this is incorrect.

(C) S²⁻ acts as a reducing agent

The sulfide ion reduces metal oxide to metal and gets oxidized to SO₂.

(D) Used for extraction of Pb from galena

Galena (PbS) follows roasting + self-reduction:

$$2PbS+3O_2\to 2PbO+2S{O}_2$$

$$PbS+2PbO\to 3Pb+S{O}_2$$

Final Answer:

A, C, D