Which of the following sulphides when heated strongly in air gives the corresponding metal?

Options

A. CuS
B. `Fe_2S_3`
C. FeS
D. HgS

Answer

To determine which of the given sulfides produces the corresponding metal when heated strongly in air, we will analyze each sulfide one by one.

### Step-by-Step Solution:

1. **Identify the Sulfides**: We have four sulfides to analyze: CuS (Copper(II) sulfide), Fe2S3 (Iron(III) sulfide), FeS (Iron(II) sulfide), and HgS (Mercury(II) sulfide).

2. **Analyze CuS**:
- When CuS is heated in air, it reacts with oxygen to form copper(II) oxide (CuO) and sulfur dioxide (SO2).
- Reaction:
\[ 2 \text{CuS} + 3 \text{O}_2 \rightarrow 2 \text{CuO} + 2 \text{SO}_2 \]
- Conclusion: This does not yield copper metal. Hence, CuS is **not** the correct answer.

3. **Analyze Fe2S3**:
- When Fe2S3 is heated in air, it produces ferrous sulfate (FeSO4) and sulfur dioxide.
- Reaction:
\[ 2 \text{Fe}_2\text{S}_3 + 9 \text{O}_2 \rightarrow 4 \text{FeSO}_4 + 6 \text{SO}_2 \]
- Conclusion: This does not yield iron metal. Hence, Fe2S3 is **not** the correct answer.

4. **Analyze FeS**:
- When FeS is heated in air, it forms iron(III) oxide (Fe2O3) and sulfur dioxide.
- Reaction:
\[ 4 \text{FeS} + 7 \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3 + 4 \text{SO}_2 \]
- Conclusion: This does not yield iron metal. Hence, FeS is **not** the correct answer.

5. **Analyze HgS**:
- When HgS is heated strongly in air, it produces mercury metal and sulfur dioxide.
- Reaction:
\[ 2 \text{HgS} + 3 \text{O}_2 \rightarrow 2 \text{Hg} + 2 \text{SO}_2 \]
- Conclusion: This does yield mercury metal. Hence, HgS is the **correct answer**.

### Final Answer:
The sulfide that when heated strongly in air gives the corresponding metal is **HgS (Mercury(II) sulfide)**.

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