Which one of the following compounds gives carboxylic acid with `HNO_(2)`?

Options

A. `C_6H_5-overset(O)overset(||)(C )-Cl`
B. `C_6H_5CONH_2`
C. `CH_3-overset(O)overset(||)(C )-O-overset(O)overset(||)(C )-CH_3`
D. `CH_3COOC_2H_5`

Answer

To solve the question "Which one of the following compounds gives carboxylic acid with `HNO_(2)`?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Compounds**: First, we need to identify the compounds given in the options. We are looking for a compound that can react with nitrous acid (HNO2) to produce a carboxylic acid.

2. **Understand the Reaction with HNO2**: Nitrous acid (HNO2) is known to react with amides to produce carboxylic acids. The general reaction involves the conversion of an amide into a carboxylic acid, releasing nitrogen gas (N2) in the process.

3. **Recognize the Amide Structure**: The structure of an amide is RCONH2, where R is a hydrocarbon group. When HNO2 reacts with an amide, the nitrogen in the amide is replaced by an oxygen atom (from the nitrous acid), forming a carboxylic acid (RCOOH) and releasing nitrogen gas.

4. **Perform the Reaction**: For example, if we take an amide like benzamide (C6H5CONH2) and react it with HNO2:
- The reaction can be represented as:
\[ C6H5CONH2 + HNO2 \rightarrow C6H5COOH + N2 + H2O \]
- Here, benzamide is converted into benzoic acid (C6H5COOH), nitrogen gas is released, and water is formed.

5. **Conclusion**: From the options provided, the compound that contains an amide functional group will be the one that gives a carboxylic acid upon reaction with HNO2.

### Final Answer:
The correct option is the one that contains an amide group, which will yield a carboxylic acid when treated with nitrous acid.

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