Which reaction does not occur in reduction process.

Options

A. `HgS+2HgOoverset(Delta)rarr 3Hg+SO_(2)`
B. `PbS+2PbO overset(Delta)rarr 3Pb+SO_(2)`
C. `ZnS+2ZnOoverset(Delta)rarr 3Zn+SO_(2)`
D. None of these

Answer

To determine which reaction does not occur in the reduction process, let's analyze the options provided in the question step by step.

### Step 1: Identify the Reactions
1. **HgS + HgO → 3Hg + SO2**
2. **PbS + 2PbO → Pb + SO2**
3. **ZnS + ZnO → Zn + SO2**
4. **None of these**

### Step 2: Understand Reduction Processes
Reduction is a process where a substance gains electrons, leading to a decrease in oxidation state. In metallurgy, reduction typically involves converting metal oxides or sulfides into pure metals.

### Step 3: Analyze Each Reaction
- **HgS + HgO → 3Hg + SO2**: This reaction involves the reduction of mercury sulfide (HgS) and mercury oxide (HgO) to produce elemental mercury (Hg) and sulfur dioxide (SO2). This is a valid reduction process.

- **PbS + 2PbO → Pb + SO2**: This reaction involves the reduction of lead sulfide (PbS) with lead oxide (PbO) to produce lead (Pb) and sulfur dioxide (SO2). This is also a valid reduction process.

- **ZnS + ZnO → Zn + SO2**: Here, zinc sulfide (ZnS) is treated with zinc oxide (ZnO) to produce zinc (Zn) and sulfur dioxide (SO2). However, zinc is a moderately reactive metal and typically does not undergo self-reduction. Instead, it would require carbon reduction at elevated temperatures.

- **None of these**: This option suggests that all the reactions are valid reduction processes.

### Step 4: Conclusion
Among the reactions analyzed, the third reaction involving zinc (ZnS + ZnO → Zn + SO2) does not occur through self-reduction due to zinc's moderate reactivity. Therefore, the correct answer to the question "Which reaction does not occur in the reduction process?" is:

**ZnS + ZnO → Zn + SO2**