Which of the following reactions of methane is incomplete combustion:

Options

A. `2CH_(4)+O_(2)overset("Cu/523K/100atm")rarr2CH_(3)OH`
B. `CH_(4)+O_(2)overset(Mo_(2)O_(3))rarrHCHO+H_(2)O`
C. `CH_(4)+O_(2)rarrC(S)+2H_(2)O(l)`
D. `CH_(2)+2O_(2)rarrCO_(2)(g)+2H_(2)O(l)`

Explanation

To determine which reaction of methane represents incomplete combustion, we need to understand the process of combustion and the products formed during complete and incomplete combustion.

### Step-by-Step Solution:

1. **Understanding Combustion**:
- Combustion is a chemical reaction that occurs when a substance reacts with oxygen, releasing energy in the form of heat and light.
- There are two types of combustion: complete and incomplete.

2. **Complete Combustion**:
- In complete combustion, methane (CH₄) reacts with a sufficient amount of oxygen (O₂) to produce carbon dioxide (CO₂) and water (H₂O).
- The reaction can be represented as:
\[ CH₄ + 2O₂ \rightarrow CO₂ + 2H₂O \]

3. **Incomplete Combustion**:
- Incomplete combustion occurs when there is insufficient oxygen available for the reaction. This leads to the formation of carbon monoxide (CO) or carbon (soot/black carbon) along with water.
- The general reaction can be represented as:
\[ 2CH₄ + O₂ \rightarrow 2CO + 4H₂O \quad \text{(produces carbon monoxide)} \]
or
\[ CH₄ + O₂ \rightarrow C + 2H₂O \quad \text{(produces carbon black)} \]

4. **Identifying the Reaction**:
- From the options provided, we need to identify which reaction produces carbon black or carbon monoxide, indicating incomplete combustion.
- The presence of carbon black (soot) is a clear indicator of incomplete combustion.

5. **Conclusion**:
- Based on the information provided, the reaction that produces carbon black is the one that represents incomplete combustion of methane. Therefore, the correct option is the one that includes carbon as a product.

### Final Answer:
The reaction of methane that represents incomplete combustion is the one that produces carbon black (soot).

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