The stopper of a bottle containing an ammonium salt is taken out. A strong smell of ammonia is given out. The salt is

Options

A. ammonium chloride
B. ammonium sulphate
C. ammonium carbonate
D. ammonium nitrate

Answer

To determine the ammonium salt that releases a strong smell of ammonia when the stopper of the bottle is removed, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Nature of the Salt**:
- The question specifies that the salt is an ammonium salt. Ammonium salts generally contain the ammonium ion (NH₄⁺).

2. **Understand the Reaction**:
- When the stopper is removed, the salt is exposed to air. The presence of air can lead to the decomposition of certain ammonium salts, releasing ammonia gas (NH₃).

3. **Consider Common Ammonium Salts**:
- Common ammonium salts include ammonium chloride (NH₄Cl), ammonium sulfate ((NH₄)₂SO₄), and ammonium carbonate ((NH₄)₂CO₃).

4. **Analyze the Decomposition**:
- Among these, ammonium carbonate is known to decompose upon exposure to air:
- The reaction can be represented as:
\[ (NH₄)₂CO₃ \rightarrow NH₄HCO₃ + NH₃ \]
- Further exposure leads to:
\[ NH₄HCO₃ \rightarrow H₂O + CO₂ + NH₃ \]

5. **Conclusion**:
- The decomposition of ammonium carbonate produces ammonia gas, which is responsible for the strong smell noted when the bottle is opened. Therefore, the salt in question is ammonium carbonate.

### Final Answer:
The salt is **ammonium carbonate**.