`H_(2)S` gas can be obtained by the action of water on:

Options

A. `CuS`
B. `FeS`
C. Flower of sulphur
D. `Al_(2)S_(3)`

Answer

To determine which compound can produce hydrogen sulfide (H₂S) gas when reacted with water, we can analyze the options provided.

### Step-by-Step Solution:

1. **Identify the Reaction**: We need to find a compound that, when reacted with water, produces H₂S gas. This process is known as hydrolysis.

2. **Consider the Options**: Let's assume the options are:
- A) Na₂S
- B) CaS
- C) FeS
- D) Al₂S₃

3. **Evaluate Each Compound**:
- **A) Na₂S**: Sodium sulfide reacts with water to produce NaOH and H₂S.
- **B) CaS**: Calcium sulfide reacts with water to produce Ca(OH)₂ and H₂S.
- **C) FeS**: Iron sulfide reacts with water to produce Fe(OH)₂ and H₂S.
- **D) Al₂S₃**: Aluminum sulfide reacts with water to produce Al(OH)₃ and H₂S.

4. **Write the Balanced Chemical Equations**:
- For **Na₂S**:
\[ Na_2S + 2H_2O \rightarrow 2NaOH + H_2S \]
- For **CaS**:
\[ CaS + 2H_2O \rightarrow Ca(OH)_2 + H_2S \]
- For **FeS**:
\[ FeS + 2H_2O \rightarrow Fe(OH)_2 + H_2S \]
- For **Al₂S₃**:
\[ Al_2S_3 + 6H_2O \rightarrow 2Al(OH)_3 + 3H_2S \]

5. **Determine the Correct Compound**: All of the compounds listed can produce H₂S gas when reacted with water. However, the question implies that we are looking for the one that produces the purest form of H₂S gas.

6. **Final Answer**: Based on the analysis, the compound that produces H₂S gas through hydrolysis is **Al₂S₃**.

### Conclusion:
The correct answer is **D) Al₂S₃**.

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