Which of the following leads to the formation of an alkyl halide -

Options

A. `C_(2)H_(5)OH overset("Red P +Br"_(2)) rarr`
B. `C_(2)H_(5)OH overset("SOCI"_(2)) rarr`
C. `C_(2)H_(5)OH overset("KBr+Cone.H"_(2)SO_(4)) rarr`
D. All

Answer

To determine which of the following leads to the formation of an alkyl halide, we will analyze the reactions involving ethanol (C2H5OH) with different reagents.

### Step 1: Reaction of Ethanol with Red Phosphorus and Bromine (Br2)
- **Reaction**: C2H5OH + Red Phosphorus + Br2
- **Mechanism**: This reaction involves a nucleophilic substitution where the bromide ion (Br-) acts as a nucleophile. The Br- ion attacks the carbon atom bonded to the hydroxyl group (OH) and substitutes it, resulting in the formation of ethyl bromide (C2H5Br).
- **Products**: C2H5Br + H3PO3

### Step 2: Reaction of Ethanol with Thionyl Chloride (SOCl2)
- **Reaction**: C2H5OH + SOCl2
- **Mechanism**: In this reaction, the chlorine ion (Cl-) from SOCl2 acts as a nucleophile and substitutes the hydroxyl group (OH) in ethanol. This leads to the formation of chloroethane (C2H5Cl).
- **Products**: C2H5Cl + SO2 + HCl

### Step 3: Reaction of Ethanol with KBr in the Presence of Concentrated H2SO4
- **Reaction**: C2H5OH + KBr + Concentrated H2SO4
- **Mechanism**: Initially, ethanol undergoes dehydration in the presence of concentrated H2SO4 to form an alkene (C2H4). Subsequently, the alkene reacts with KBr, where the bromide ion (Br-) adds to the alkene, leading to the formation of ethyl bromide (C2H5Br).
- **Products**: C2H5Br

### Conclusion
All three reactions lead to the formation of alkyl halides:
1. Ethanol with Red Phosphorus and Br2 gives ethyl bromide.
2. Ethanol with SOCl2 gives chloroethane.
3. Ethanol with KBr in the presence of concentrated H2SO4 gives ethyl bromide.

Thus, the answer is that all of these reactions lead to the formation of alkyl halides.

### Final Answer
**All of these are correct.**

---