Which of the following sulphides when heated without undergoing separated reduction of oxide ?

Options

A. `Cu_(2)S`
B. FeS
C. HgS
D. ZnS

Explanation

To solve the question, we need to determine which of the given sulfides can be heated to yield a metal directly without forming an oxide. Let's analyze each sulfide one by one.

### Step-by-Step Solution:

1. **Identify the Sulfides**: The sulfides we need to analyze are:
- Copper sulfide (CuS)
- Iron sulfide (FeS)
- Mercury sulfide (HgS)
- Zinc sulfide (ZnS)

2. **Write the Reactions**:
- **Copper Sulfide (CuS)**:
\[ \text{CuS} + \text{O}_2 \rightarrow \text{CuO} + \text{SO}_2 \]
(Forms copper oxide)

- **Iron Sulfide (FeS)**:
\[ \text{FeS} + \text{O}_2 \rightarrow \text{Fe} + \text{SO}_2 \]
(Forms iron directly without forming an oxide)

- **Mercury Sulfide (HgS)**:
\[ \text{HgS} + \text{O}_2 \rightarrow \text{HgO} + \text{SO}_2 \]
(Forms mercury oxide)

- **Zinc Sulfide (ZnS)**:
\[ \text{ZnS} + \text{O}_2 \rightarrow \text{ZnO} + \text{SO}_2 \]
(Forms zinc oxide)

3. **Analyze the Reactions**: From the reactions:
- Copper sulfide, mercury sulfide, and zinc sulfide all produce their respective metal oxides when heated.
- Iron sulfide, however, produces iron directly without the formation of an oxide.

4. **Conclusion**: Therefore, the sulfide that can be heated to yield a metal directly without forming an oxide is **Iron Sulfide (FeS)**.

### Final Answer:
The correct option is **Iron Sulfide (FeS)**.

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