In which of the following, homolytic bond fission takes place :

Options

A. Alkaline hydrolysis of ethylchloride
B. Addition of HBr to double bond.
C. Photochlorination of methane
D. Nitration of benzene

Answer

To determine in which of the given options homolytic bond fission takes place, we first need to understand what homolytic bond fission is.

### Step-by-Step Solution:

1. **Understanding Homolytic Bond Fission**:
- Homolytic bond fission occurs when a bond breaks in such a way that each of the bonded atoms takes one of the shared electrons. This results in the formation of two free radicals.

2. **Analyzing the Options**:
- We need to evaluate each option to see if it involves a process where homolytic bond fission occurs.

3. **Option 1: Alkaline Hydrolysis of Ethyl Chloride**:
- In this reaction, ethyl chloride reacts with a base (alkali) to form ethyl alcohol. This reaction involves nucleophilic substitution, not homolytic fission.
- **Conclusion**: No homolytic bond fission occurs here.

4. **Option 2: Addition of HBr to a Double Bond**:
- In this reaction, HBr adds across a double bond, which involves the formation of a carbocation intermediate. This is an electrophilic addition reaction and does not involve homolytic bond fission.
- **Conclusion**: No homolytic bond fission occurs here.

5. **Option 3: Photochlorination of Methane**:
- In this reaction, methane reacts with chlorine under UV light. The bond between chlorine atoms (Cl-Cl) undergoes homolytic fission due to the energy provided by UV light, producing two chlorine radicals. This is a classic example of a reaction that involves homolytic bond fission.
- **Conclusion**: Yes, homolytic bond fission occurs here.

6. **Option 4: Another Reaction (not specified)**:
- Without specific details, we cannot analyze this option. However, if it does not involve free radicals or photochemical processes, it likely does not involve homolytic bond fission.
- **Conclusion**: Likely no homolytic bond fission occurs here.

### Final Answer:
The correct option where homolytic bond fission takes place is **Option 3: Photochlorination of Methane**.