Which of the following compounds will give `N_(2)(g)` on treatment with `HNO_(2)`

Options

A. `C_(2)H_(5)-NH_(2)`
B. `C_(6)H_(5)-NH-CH_(3)`
C. `NH_(2)-CO-NH_(2)`
D. `C_(6)H_(5)-CO-NH_(2)`

Answer

To determine which of the given compounds will produce nitrogen gas (N₂) when treated with nitrous acid (HNO₂), we need to analyze each compound's reactivity with HNO₂.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have the following compounds to analyze:
- C₂H₅NH₂ (ethylamine)
- A secondary amine (not specified)
- NH₂C(=O)NH₂ (urea)
- C₆H₅C(=O)NH₂ (benzamide)

2. **Reaction of Ethylamine (C₂H₅NH₂)**:
- Ethylamine is a primary amine. When it reacts with HNO₂, it forms a diazonium salt (C₂H₅N₂⁺Cl⁻). This salt is unstable and decomposes upon heating, releasing nitrogen gas (N₂) and forming a carbocation (C₂H₅⁺) and chloride ion (Cl⁻).
- **Conclusion**: C₂H₅NH₂ will produce N₂ gas.

3. **Reaction of Secondary Amine**:
- Secondary amines do not form stable diazonium salts when treated with HNO₂. Therefore, they do not release N₂ gas.
- **Conclusion**: The secondary amine will not produce N₂ gas.

4. **Reaction of Urea (NH₂C(=O)NH₂)**:
- Urea, when treated with HNO₂, forms a stable diazonium salt (NH₂C(=O)N₂⁺). This salt does not decompose to release nitrogen gas.
- **Conclusion**: Urea will not produce N₂ gas.

5. **Reaction of Benzamide (C₆H₅C(=O)NH₂)**:
- Benzamide reacts with HNO₂ to form a diazonium salt (C₆H₅C(=O)N₂⁺). Similar to urea, this salt is stabilized by resonance and does not release N₂ gas.
- **Conclusion**: Benzamide will not produce N₂ gas.

### Final Answer:
The only compound that will produce nitrogen gas (N₂) upon treatment with HNO₂ is **C₂H₅NH₂ (ethylamine)**.