How many of the structurally isomerie pentyl alcohols will give immediate turbidity in Lucas test?

Explanation

To determine how many structurally isomeric pentyl alcohols will give immediate turbidity in the Lucas test, we need to understand the nature of the alcohols and the reaction conditions.

### Step-by-Step Solution:

1. **Understanding the Lucas Test**:
The Lucas test is used to differentiate between primary, secondary, and tertiary alcohols based on their reactivity with hydrochloric acid (HCl) in the presence of anhydrous zinc chloride (ZnCl2). Tertiary alcohols react immediately to form a stable carbocation, leading to immediate turbidity. Secondary alcohols show turbidity after a few minutes, while primary alcohols take much longer to react.

2. **Identifying Pentyl Alcohols**:
Pentyl alcohols (C5H12O) can be classified based on the position of the hydroxyl (-OH) group. The possible structural isomers of pentyl alcohol include:
- 1-Pentanol (primary)
- 2-Pentanol (secondary)
- 3-Pentanol (secondary)
- 2-Methyl-1-butanol (primary)
- 3-Methyl-1-butanol (primary)
- 2-Methyl-2-butanol (tertiary)
- 3-Methyl-2-butanol (tertiary)

3. **Analyzing Reactivity**:
- **Tertiary Alcohols**: These will give immediate turbidity. In our list, 2-Methyl-2-butanol and 3-Methyl-2-butanol are tertiary alcohols.
- **Secondary Alcohols**: These will show turbidity after some time. 2-Pentanol and 3-Pentanol are secondary alcohols.
- **Primary Alcohols**: These will take longer to show turbidity. 1-Pentanol, 2-Methyl-1-butanol, and 3-Methyl-1-butanol are primary alcohols.

4. **Conclusion**:
The only isomers that will give immediate turbidity in the Lucas test are the tertiary alcohols. Therefore, there are **2 structurally isomeric pentyl alcohols** that will give immediate turbidity.

### Final Answer:
**2 structurally isomeric pentyl alcohols will give immediate turbidity in the Lucas test.**