In the reaction, `Cl_(2)+CH_(4)overset(hv)toCH_(3)Cl+HCl` presence of a small amount of oxygen

Options

A. increases the rate of reaction for a brief period of time
B. decreases the rate of reaction for a brief period of time
C. does not affect the rate of reaction
D. completely stops the reaction

Explanation

To solve the question regarding the reaction of `Cl2 + CH4` in the presence of a small amount of oxygen, we need to analyze the reaction step by step.

### Step-by-Step Solution:

1. **Identify the Reaction Type**: The reaction involves the chlorination of methane (CH4) in the presence of chlorine gas (Cl2) and is initiated by heat or light (hv). The presence of oxygen can influence the reaction pathway.

2. **Initiation Step**: In the presence of light or heat, Cl2 will dissociate into two chlorine radicals (Cl·):
\[ \text{Cl}_2 \xrightarrow{hv} 2 \text{Cl}· \]

3. **Propagation Steps**: The chlorine radical can then react with methane to form methyl radical (CH3·) and hydrogen chloride (HCl):
\[ \text{Cl}· + \text{CH}_4 \rightarrow \text{CH}_3· + \text{HCl} \]

4. **Formation of Products**: The methyl radical can further react with another chlorine molecule (Cl2) to form chloromethane (CH3Cl):
\[ \text{CH}_3· + \text{Cl}_2 \rightarrow \text{CH}_3\text{Cl} + \text{Cl}· \]

5. **Role of Oxygen**: The presence of a small amount of oxygen can lead to the formation of peroxy radicals, which can further react with the chlorinated products or radicals, potentially leading to different products or side reactions. However, in this specific reaction, the main products remain chloromethane and HCl.

6. **Final Products**: The main products of the reaction are:
- Chloromethane (CH3Cl)
- Hydrogen chloride (HCl)

### Summary of the Reaction:
The overall reaction can be summarized as:
\[ \text{Cl}_2 + \text{CH}_4 \xrightarrow{hv} \text{CH}_3\text{Cl} + \text{HCl} \]
with the presence of a small amount of oxygen potentially influencing the reaction pathway, but not significantly altering the main products.