`C_(6)H_(5)COOH+A overset("conc."H_(2)SO_(4))to N_(2)+CO_(2)+C_(6)H_(5)NH_(2)`
The above reaction is a Schmidt reaction. Here A is –

Options

A. Polyprotic acid
B. Monobasic acid
C. Monoacid base
D. None

Answer

To solve the question regarding the Schmidt reaction involving benzoic acid (C₆H₅COOH), we need to identify the reactant A that leads to the formation of nitrogen (N₂), carbon dioxide (CO₂), and aniline (C₆H₅NH₂) when treated with concentrated sulfuric acid (H₂SO₄).

### Step-by-Step Solution:

1. **Understanding the Schmidt Reaction**:
The Schmidt reaction is a chemical reaction where a carboxylic acid reacts with hydrazoic acid (HN₃) in the presence of an acid catalyst, typically concentrated sulfuric acid. This reaction results in the formation of an amine and the release of nitrogen gas.

2. **Identifying the Reactants**:
In the given reaction, we start with benzoic acid (C₆H₅COOH). The product of the reaction includes nitrogen gas (N₂), carbon dioxide (CO₂), and aniline (C₆H₅NH₂).

3. **Determining Reactant A**:
The reactant A in this reaction is hydrazoic acid (HN₃). In the Schmidt reaction, hydrazoic acid acts as the source of the azide ion (N₃⁻), which is crucial for the reaction to proceed.

4. **Reaction Mechanism**:
When benzoic acid reacts with hydrazoic acid in the presence of concentrated sulfuric acid, the azide ion (from HN₃) interacts with the carboxylic acid. This leads to the formation of an intermediate that ultimately decomposes to yield aniline, carbon dioxide, and nitrogen gas.

5. **Final Conclusion**:
Therefore, the reactant A in the given Schmidt reaction is hydrazoic acid (HN₃).

### Final Answer:
A is hydrazoic acid (HN₃).