Which of the following compound liberates acidic gas during its hydrolysis?

Options

A. `Ca_(3)P_(2)`
B. `AlN`
C. `Al_(2)S_(3)`
D. `CaH_(2)`

Explanation

To determine which compound liberates an acidic gas during hydrolysis, we will analyze each option provided in the question step by step.

### Step 1: Analyze Option 1 - Ca3P2
- When Ca3P2 (calcium phosphide) undergoes hydrolysis, it reacts with water to produce calcium hydroxide (Ca(OH)2) and phosphine (PH3).
- **Reaction:**
\[ \text{Ca}_3\text{P}_2 + 6 \text{H}_2\text{O} \rightarrow 3 \text{Ca(OH)}_2 + 2 \text{PH}_3 \]
- PH3 is a basic gas, not an acidic gas. Therefore, this option does not liberate an acidic gas.

### Step 2: Analyze Option 2 - AlN
- When AlN (aluminum nitride) reacts with water, it produces aluminum hydroxide (Al(OH)3) and ammonia (NH3).
- **Reaction:**
\[ \text{AlN} + 3 \text{H}_2\text{O} \rightarrow \text{Al(OH)}_3 + \text{NH}_3 \]
- NH3 is also basic in nature. Thus, this option does not liberate an acidic gas.

### Step 3: Analyze Option 3 - Al2S3
- When Al2S3 (aluminum sulfide) undergoes hydrolysis, it reacts with water to form aluminum hydroxide (Al(OH)3) and hydrogen sulfide (H2S).
- **Reaction:**
\[ \text{Al}_2\text{S}_3 + 6 \text{H}_2\text{O} \rightarrow 2 \text{Al(OH)}_3 + 3 \text{H}_2\text{S} \]
- H2S is known to be an acidic gas. Therefore, this option liberates an acidic gas during hydrolysis.

### Step 4: Analyze Option 4 - CaS2
- When CaS2 (calcium disulfide) reacts with water, it produces calcium hydroxide (Ca(OH)2) and hydrogen sulfide (H2S).
- **Reaction:**
\[ \text{CaS}_2 + 2 \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{H}_2\text{S} \]
- H2S is again an acidic gas. However, since we already found that Al2S3 liberates an acidic gas, we need to identify the primary answer.

### Conclusion
The compound that liberates an acidic gas during hydrolysis is **Al2S3** (option 3).

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