Consider the following statements:
Phenyl diazonium salts form azo dye with
I. aniline
II. Phenol
III. N, N - dimethyl aniline
IV. Anisole (methoxybenzene)
The correct statements is

Options

A. 2,3,4 are correct
B. 1,3 and 4 are correct
C. 1,2 and 4 are correct
D. 1,2 and 3 are correct

Answer

To solve the problem, we need to determine which of the given compounds can form azo dyes with phenyl diazonium salts.

### Step-by-step Solution:

1. **Understanding Phenyl Diazonium Salts**:
- Phenyl diazonium salts have the structure C6H5-N2^+X^-, where X is a counterion (like Cl^-).
- They are weak electrolytes and can undergo diazo coupling reactions.

2. **Identifying the Reactivity of Compounds**:
- Diazo coupling occurs with aromatic compounds that have activating groups. These activating groups include:
- Hydroxyl group (-OH)
- Amino group (-NH2)
- Alkylamino groups (-NHR, -NR2)

3. **Analyzing Each Statement**:
- **I. Aniline (C6H5-NH2)**:
- Aniline has an amino group (-NH2), which is an activating group. Therefore, it can form an azo dye with phenyl diazonium salts.
- **II. Phenol (C6H5-OH)**:
- Phenol has a hydroxyl group (-OH), which is also an activating group. Thus, it can form an azo dye with phenyl diazonium salts.
- **III. N,N-Dimethyl aniline (C6H5-N(CH3)2)**:
- N,N-Dimethyl aniline has a dimethylamino group (-N(CH3)2), which is an activating group. Therefore, it can also form an azo dye with phenyl diazonium salts.
- **IV. Anisole (C6H5-OCH3)**:
- Anisole has a methoxy group (-OCH3), which is a weakly activating group. However, it is not sufficiently activating for diazo coupling to occur with phenyl diazonium salts. Therefore, it cannot form an azo dye.

4. **Conclusion**:
- The correct statements are I (Aniline), II (Phenol), and III (N,N-Dimethyl aniline).
- The incorrect statement is IV (Anisole).

### Final Answer:
The correct statements are I, II, and III.