Which of the following reaction(s) can be used for the preparation of alkyl halides?
(I) `CH_(3)CH_(2)OH+HCl overset("anhyd." ZnCl_(2))to`
(II) `CH_(3)CH_(2) OH+HCl to`
(III) `(CH_(3))_(3)COH+HCl to`
(IV) `(CH_(3))_(2)CHOH+HCl overset("anhyd." ZnCl_(2))to`

Options

A. (IV) only
B. (III) and (IV) only
C. (I), (III) and (IV) only
D. (I) and (II) only

Explanation

To determine which of the given reactions can be used for the preparation of alkyl halides, we need to analyze each reaction based on the type of alcohol (primary, secondary, or tertiary) and the presence of reagents (HCl and anhydrous ZnCl2).

### Step-by-Step Solution:

1. **Reaction I: `CH₃CH₂OH + HCl overset("anhyd." ZnCl₂) to`**
- This reaction involves a primary alcohol (ethanol) reacting with HCl in the presence of anhydrous ZnCl₂.
- Primary alcohols can react with HCl and ZnCl₂ to form alkyl halides (ethyl chloride in this case).
- **Conclusion**: This reaction can be used to prepare an alkyl halide.

2. **Reaction II: `CH₃CH₂OH + HCl to`**
- This reaction also involves a primary alcohol (ethanol) reacting with HCl, but it lacks the anhydrous ZnCl₂.
- While primary alcohols can react with HCl, the absence of ZnCl₂ may lead to incomplete reaction or side products.
- **Conclusion**: This reaction is less effective for preparing an alkyl halide.

3. **Reaction III: `(CH₃)₃COH + HCl to`**
- This reaction involves a tertiary alcohol (tert-butanol) reacting with HCl.
- Tertiary alcohols react rapidly with HCl to form alkyl halides without the need for anhydrous ZnCl₂ due to the formation of a stable tertiary carbocation.
- **Conclusion**: This reaction can be used to prepare an alkyl halide.

4. **Reaction IV: `(CH₃)₂CHOH + HCl overset("anhyd." ZnCl₂) to`**
- This reaction involves a secondary alcohol (isopropanol) reacting with HCl in the presence of anhydrous ZnCl₂.
- Secondary alcohols can react with HCl and ZnCl₂ to form alkyl halides (isopropyl chloride in this case).
- **Conclusion**: This reaction can be used to prepare an alkyl halide.

### Final Conclusion:
The reactions that can be used for the preparation of alkyl halides are:
- Reaction I (Primary alcohol with ZnCl₂)
- Reaction III (Tertiary alcohol without ZnCl₂)
- Reaction IV (Secondary alcohol with ZnCl₂)

Thus, the correct options are I, III, and IV.