In the chlorination of Methane which of the following reaction involve in the chain termination step .

Options

A. `Cl-Cl to 2dotCl`
B. `dotCl+dotCl to Cl-Cl`
C. `dotCH_3+dotCl toCH_3-Cl`
D. `dotCH_3+Cl-Cl to CH_3-Cl+dotCl`

Explanation

To determine which reaction involves the chain termination step in the chlorination of methane, we need to understand the overall mechanism of the reaction. The chlorination of methane is a free radical reaction that occurs in three main stages: initiation, propagation, and termination.

### Step-by-Step Solution:

1. **Initiation Step:**
- The reaction begins with the homolytic cleavage of the chlorine molecule (Cl2) in the presence of light. This process generates two chlorine free radicals (Cl•).
- **Reaction:**
\[ \text{Cl}_2 \xrightarrow{\text{light}} 2 \text{Cl}• \]

2. **Propagation Steps:**
- The chlorine free radical (Cl•) then reacts with methane (CH4) to form a methyl free radical (CH3•) and hydrochloric acid (HCl).
- **Reaction:**
\[ \text{Cl}• + \text{CH}_4 \rightarrow \text{CH}_3• + \text{HCl} \]
- The methyl free radical (CH3•) can then react with another chlorine molecule (Cl2) to produce methyl chloride (CH3Cl) and regenerate another chlorine free radical (Cl•).
- **Reaction:**
\[ \text{CH}_3• + \text{Cl}_2 \rightarrow \text{CH}_3\text{Cl} + \text{Cl}• \]

3. **Termination Step:**
- The termination step occurs when two free radicals combine to form a stable product. In this case, the methyl free radical (CH3•) can react with the chlorine free radical (Cl•) to form methyl chloride (CH3Cl).
- **Reaction:**
\[ \text{CH}_3• + \text{Cl}• \rightarrow \text{CH}_3\text{Cl} \]

### Conclusion:
The reaction that involves the chain termination step is the combination of the methyl free radical and the chlorine free radical to form methyl chloride. Therefore, the correct answer is option C.