Which metal sulphide is soluble in excess `NH_(3)` solution?

Options

A. ZnS
B. MnS
C. FeS
D. `Cr_(2)S_(3)`

Explanation

To determine which metal sulfide is soluble in excess ammonia solution, we will analyze the solubility of the given metal sulfides: zinc sulfide (ZnS), manganese sulfide (MnS), iron sulfide (FeS), and chromium(III) sulfide (Cr2S3).

### Step-by-Step Solution:

1. **Identify the Metal Sulfides:**
We have four metal sulfides to consider:
- Zinc sulfide (ZnS)
- Manganese sulfide (MnS)
- Iron sulfide (FeS)
- Chromium(III) sulfide (Cr2S3)

2. **Understand Solubility in Ammonia:**
The solubility of metal sulfides in ammonia can vary. Generally, some metal sulfides do not dissolve in excess ammonia due to their low solubility product (Ksp).

3. **Analyze Each Metal Sulfide:**
- **Zinc Sulfide (ZnS):**
- ZnS is known to have a low Ksp and does not dissolve in excess ammonia.
- **Manganese Sulfide (MnS):**
- MnS also has a low Ksp and is insoluble in excess ammonia.
- **Iron Sulfide (FeS):**
- FeS similarly has a low Ksp and does not dissolve in excess ammonia.
- **Chromium(III) Sulfide (Cr2S3):**
- Cr2S3 reacts with excess ammonia (6 moles of NH3) to form a soluble complex, specifically the hexamine chromium(III) ion, \([Cr(NH_3)_6]^{3+}\), along with sulfide ions in solution.

4. **Conclusion:**
Based on the analysis, only chromium(III) sulfide (Cr2S3) is soluble in excess ammonia solution. Therefore, the correct answer is:
- **Chromium(III) sulfide (Cr2S3)** is soluble in excess NH3.

### Final Answer:
**Chromium(III) sulfide (Cr2S3)** is the metal sulfide that is soluble in excess ammonia solution.

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