Which of the following reactants is suitable for preparation of methane and ethane by using one step only ?

Options

A. `H_(2)C = CH_(2)`
B. `CH_(3)OH`
C. `CH_(3) - Br`
D. `CH_(3) - CH_(2) - OH`

Explanation

To determine which reactant is suitable for the preparation of methane (CH₄) and ethane (C₂H₆) in one step, we will analyze each of the provided options: ethene, methanol, methylbromide, and ethanol.

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants given are:
- Ethene (C₂H₄)
- Methanol (CH₃OH)
- Methylbromide (CH₃Br)
- Ethanol (C₂H₅OH)

2. **Analyze Each Reactant**:
- **Ethene (C₂H₄)**:
- Ethene can undergo hydrogenation to form ethane, but it cannot produce methane in one step.
- **Methanol (CH₃OH)**:
- Methanol can be converted to methane through reduction, but this typically requires multiple steps and is not suitable for producing ethane in one step.
- **Methylbromide (CH₃Br)**:
- Methylbromide can be reduced to methane and can also be used to produce ethane when treated with sodium in dry ether. This can be done in one step.
- **Ethanol (C₂H₅OH)**:
- Ethanol can be dehydrated to form ethene, but it does not directly yield methane in one step.

3. **Conclusion**:
- The only reactant that allows for the preparation of both methane and ethane in one step is **methylbromide (CH₃Br)**.
- When methylbromide undergoes catalytic reduction or reacts with sodium in dry ether, it can yield both methane and ethane.

### Final Answer:
The suitable reactant for the preparation of methane and ethane in one step is **methylbromide (CH₃Br)**.

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