Match List - I with List - II.

Choose the correct answer from the options given below:

(A)-(I), (B)-(II), (C)-(III), (D)-(IV)

The correct answer is Option 2. (A)-(I), (B)-(II), (C)-(III), (D)-(IV)

Let us break down the processes and understand why the correct matching is (A)-(I), (B)-(II), (C)-(III), and (D)-(IV):

(A) PbS → PbO (Roasting)

Roasting is a process where sulfide ores are heated in the presence of oxygen, converting the sulfide to an oxide and releasing sulfur dioxide gas. In this case, lead sulfide (PbS) is heated in the presence of oxygen to form lead oxide (PbO) and sulfur dioxide (SO₂).

Reaction:

\(2PbS + 3O_2 \longrightarrow 2PbO + 2SO_2\)

Roasting is used for sulfide ores like PbS, which makes (A)-(I) correct.

(B) CaCO₃ → CaO (Calcination)

Calcination involves heating a substance in the absence or limited supply of air. This is commonly done for carbonates to drive off carbon dioxide (CO₂), leaving behind the metal oxide. In this case, calcium carbonate (CaCO₃) is heated to form calcium oxide (CaO) and carbon dioxide (CO₂).

Reaction:

\(CaCO_3 \overset{\Delta }{\longrightarrow} CaO + CO_2\)

This process is calcination, so (B)-(II) is correct.

(C) ZnS → Zn (Carbon Reduction)

Carbon reduction involves the reduction of metal oxides using carbon or carbon monoxide (as a reducing agent).

Zinc sulfide (ZnS) is first roasted to form zinc oxide (ZnO), and then ZnO is reduced by carbon (usually coke) to produce zinc (Zn).

Reactions:

\(2ZnS + 3O_2 \longrightarrow 2ZnO + 2SO_2 \quad (\text{Roasting})\)

\(ZnO + C \longrightarrow Zn + CO\)

The second step is carbon reduction, making (C)-(III) correct.

(D) Cu₂S → Cu (Self-Reduction)

Self-reduction, or auto-reduction, occurs when a part of the metal sulfide reduces another part of the same metal sulfide without using an external reducing agent. In the case of copper(I) sulfide (Cu₂S), it undergoes self-reduction when heated in the presence of air. A portion of the Cu₂S is oxidized to form copper(I) oxide (Cu₂O), and then Cu₂O reacts with the remaining Cu₂S to produce copper metal (Cu).

Reactions:

\(2Cu_2S + 3O_2 \longrightarrow 2Cu_2O + 2SO_2\)

\(Cu_2O + Cu_2S \longrightarrow 6Cu + SO_2 \)

This process is self-reduction, which makes (D)-(IV) correct. This is why the correct answer is: (A)-(I), (B)-(II), (C)-(III), (D)-(IV).