Amino `(-NH_(2))` group is susceptible to oxidation by `HNO_(3)`, therefore, nitration is done in the presence of :

Options

A. dil `H_(2)SO_(4)`
B. `CS_(2)` at `0^(@)C`
C. `CH_(3),COCl`
D. Water.

Explanation

To solve the question regarding the nitration of an amino group (-NH₂) in the presence of HNO₃, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Problem**:
- The amino group (-NH₂) is known to be susceptible to oxidation when treated with nitric acid (HNO₃). This means that if we directly attempt to nitrate an aromatic compound containing an amino group, the amino group may get oxidized instead of allowing nitration to occur.

2. **Identifying the Need for Protection**:
- To prevent the oxidation of the amino group during the nitration process, we need to protect it. This is a common practice in organic chemistry when a functional group is reactive under certain conditions.

3. **Choosing a Protecting Group**:
- A suitable protecting group for the amino group is an acyl group. Common reagents for this purpose include acetyl chloride (CH₃COCl) or acetic anhydride ((CH₃CO)₂O). These reagents will react with the amino group to form an amide, which is less reactive towards oxidation.

4. **Performing the Protection Reaction**:
- The amino group (-NH₂) reacts with acetyl chloride or acetic anhydride to form an N-acetyl derivative. The reaction can be represented as:
\[ \text{Aniline} + \text{Acetyl Chloride} \rightarrow \text{N-Acetylaniline} + \text{HCl} \]
- This protects the amino group, converting it to N-acetyl aniline (NHCOCH₃).

5. **Nitration Reaction**:
- After the amino group is protected, the next step is to carry out the nitration. The nitrating mixture typically consists of concentrated HNO₃ and H₂SO₄. The nitration can occur without the risk of oxidizing the amino group.
- The nitration will yield nitro derivatives at the ortho and para positions relative to the acylated amino group.

6. **Final Product**:
- Once nitration is complete, the protecting group can be removed (if necessary) to regenerate the amino group, yielding the final product.

### Conclusion:
To summarize, the nitration of an aromatic compound containing an amino group is done in the presence of acetyl chloride or acetic anhydride to protect the amino group from oxidation by HNO₃.