How many of the structurally isomeric pentyl alcohols will produce immediate turbidity in Lucas test?

Explanation

To determine how many structurally isomeric pentyl alcohols will produce immediate turbidity in the Lucas test, we need to analyze the structure of pentyl alcohols and their reactivity in the Lucas test.

### 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 concentrated hydrochloric acid (HCl).
- Primary alcohols react slowly and may take up to 30 minutes to show turbidity.
- Secondary alcohols react faster, typically within 5 to 10 minutes.
- Tertiary alcohols react almost immediately, often within 30 seconds, producing a cloudy solution due to the formation of an insoluble alkyl halide.

2. **Identifying Pentyl Alcohols**:
Pentyl alcohols are alcohols with five carbon atoms. The general formula for pentyl alcohol is C5H11OH. The 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 Each Isomer**:
- **1-Pentanol**: Primary alcohol, will not produce immediate turbidity.
- **2-Pentanol**: Secondary alcohol, will not produce immediate turbidity.
- **3-Pentanol**: Secondary alcohol, will not produce immediate turbidity.
- **2-Methyl-1-butanol**: Primary alcohol, will not produce immediate turbidity.
- **3-Methyl-1-butanol**: Primary alcohol, will not produce immediate turbidity.
- **2-Methyl-2-butanol**: Tertiary alcohol, will produce immediate turbidity.
- **3-Methyl-2-butanol**: Tertiary alcohol, will produce immediate turbidity.

4. **Conclusion**:
Among the isomeric pentyl alcohols, only the tertiary alcohols (2-Methyl-2-butanol and 3-Methyl-2-butanol) will produce immediate turbidity in the Lucas test. Therefore, there are **2 structurally isomeric pentyl alcohols** that will produce immediate turbidity.

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