An isomer of `C_(6)H_(14)` forms three monochloro derivaties. The isomer may be- (Excluding stereo isomer)

Options

A. neo-pentane
B. n-hexane
C. 2, 3-dimethylbutane
D. iso-hexane

Answer

To determine which isomer of C6H14 forms three monochloro derivatives, we need to analyze the possible structural isomers of hexane and their reactivity towards chlorination.

### Step-by-Step Solution:

1. **Identify the Molecular Formula**:
The molecular formula given is C6H14, which indicates that we are dealing with hexane and its isomers.

2. **List Possible Isomers**:
The possible structural isomers of C6H14 include:
- n-Hexane (straight-chain)
- 2-Methylpentane
- 3-Methylpentane
- 2,2-Dimethylbutane
- 2,3-Dimethylbutane
- 3,3-Dimethylbutane
- Isohexane (2-Methylpentane)

3. **Analyze n-Hexane**:
- Structure: CH3-CH2-CH2-CH2-CH2-CH3
- When chlorinated, the chlorination can occur at:
- 1st carbon: 1-chlorohexane
- 2nd carbon: 2-chlorohexane
- 3rd carbon: 3-chlorohexane
- The 4th and 5th carbons are equivalent to the 2nd and 3rd, respectively, hence they do not yield new isomers.
- Total unique monochloro derivatives = 3.

4. **Analyze 2,3-Dimethylbutane**:
- Structure: (CH3)2CH-CH(CH3)-CH3
- All the carbons in this structure are equivalent in terms of their environment, leading to only one unique monochloro derivative.

5. **Analyze Isohexane (2-Methylpentane)**:
- Structure: CH3-CH(CH3)-CH2-CH2-CH3
- The chlorination can occur at:
- 1st carbon: 1-chloro-2-methylpentane
- 2nd carbon: 2-chloro-2-methylpentane
- 3rd carbon: 3-chloro-2-methylpentane
- 4th carbon: 4-chloro-2-methylpentane
- Total unique monochloro derivatives = 5.

6. **Conclusion**:
After analyzing the isomers, we find that n-hexane is the only isomer that produces exactly three unique monochloro derivatives.

### Final Answer:
The isomer of C6H14 that forms three monochloro derivatives is **n-Hexane**.