For the preparation of chloroethane,

Options

A. `HCl` gas is passed through ethanol.
B. Ethanol is treated with thionyl chloride in the presence of dimethyl amine or pyride.
C. Ethyl sulphide is treated with hydrogen chloride.
D. Any of the above methods can be empolyed.

Explanation

**Step-by-Step Solution for the Preparation of Chloroethane:**

1. **Identify Chloroethane:**
- Chloroethane is an alkyl halide with the molecular formula C2H5Cl. It consists of a two-carbon chain (ethane) with a chlorine atom replacing one hydrogen atom.

2. **Consider the Methods for Preparation:**
- The question asks for methods to prepare chloroethane. We will evaluate different reactions involving ethanol (C2H5OH) and other reagents.

3. **Method 1: Reaction of Ethanol with HCl:**
- When ethanol is treated with hydrogen chloride (HCl), a substitution reaction is expected. However, the bond in HCl is strong, and without a catalyst (like ZnCl2), this reaction does not proceed effectively.
- **Conclusion:** This method is not suitable for preparing chloroethane.

4. **Method 2: Darzen's Halogenation:**
- The second method involves treating ethanol with thionyl chloride (SOCl2) in the presence of a base such as pyridine.
- The reaction can be summarized as follows:
\[ \text{C2H5OH} + \text{SOCl2} \rightarrow \text{C2H5Cl} + \text{SO2} + \text{HCl} \]
- This reaction effectively replaces the -OH group in ethanol with a chlorine atom, resulting in chloroethane.
- **Conclusion:** This method is valid and will produce chloroethane.

5. **Method 3: Ethyl Sulfide with HCl:**
- The question also mentions the reaction of ethyl sulfide with hydrogen chloride. However, this reaction does not yield chloroethane.
- **Conclusion:** This method is not applicable for the preparation of chloroethane.

6. **Final Answer:**
- Based on the evaluations, the only valid method for the preparation of chloroethane is through Darzen's halogenation using thionyl chloride and pyridine. Therefore, the answer is:
- **Option B: Ethanol with Thionyl Chloride in the presence of Pyridine.**

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