p-Chloroaniline and anilinium hydrochloride can be distinguished by :

Options

A. Sandmeyer reaction
B. ` NaHCO_3`
C. `AgNO_3`
D. Carbylamine test

Explanation

To distinguish between p-chloroaniline and anilinium hydrochloride, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Compounds**:
- p-Chloroaniline (C6H4ClNH2) has an amino group (-NH2) and a chlorine atom (Cl) at the para position on the benzene ring.
- Anilinium hydrochloride (C6H7N·HCl) is the protonated form of aniline, where the amino group is positively charged due to the addition of a hydrogen ion (H+) from hydrochloric acid (HCl).

2. **Understand the Chemical Properties**:
- p-Chloroaniline contains a chlorine atom that can act as a leaving group.
- Anilinium hydrochloride contains a chloride ion (Cl-) that is part of the salt.

3. **Perform a Reaction Test**:
- To distinguish between the two compounds, we can perform a reaction with silver nitrate (AgNO3).
- When AgNO3 is added to anilinium hydrochloride, the chloride ion (Cl-) will react with silver ions (Ag+) to form silver chloride (AgCl), which is a white precipitate.

4. **Observe the Results**:
- If the white precipitate of AgCl forms, it indicates the presence of anilinium hydrochloride.
- If no precipitate forms, it indicates the presence of p-chloroaniline, as the chlorine in this compound is part of the aromatic structure and cannot be displaced.

5. **Conclusion**:
- Therefore, the test using AgNO3 allows us to distinguish between p-chloroaniline and anilinium hydrochloride based on the formation of a white precipitate.

### Final Answer:
The compounds can be distinguished by using **AgNO3**, which will produce a white precipitate of AgCl in the case of anilinium hydrochloride.

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