Which one of the following belongs to -I group ?

Options

A. `-C_(6)H_(5)`
B. `-CH_(2)CH_(2)CH_(3)`
C. `-C_(2)H_(5)`
D. `(CH_(3))_(2)CH-`

Explanation

To determine which group belongs to the -I (minus inductive effect) group, we need to understand the concept of inductive effect and the classification of groups based on their electron-donating or electron-withdrawing properties.

### Step-by-Step Solution:

1. **Understand Inductive Effect**:
- Inductive effect refers to the permanent polarization of a bond due to the electronegativity difference between atoms. It can be either positive (+I) or negative (-I).
- +I groups are electron-donating groups, while -I groups are electron-withdrawing groups.

2. **Identify the Groups**:
- The options provided are:
- A) C6H5 (Phenyl group)
- B) CH2
- C) CH3 (Methyl group)
- D) C2H5 (Ethyl group)
- E) CH (Allyl group)

3. **Classify Each Group**:
- **C6H5 (Phenyl group)**: This group is known to be electron-withdrawing due to resonance and its unsaturated nature. It exhibits a -I effect.
- **CH2 (Methylene group)**: This is an alkyl group and is electron-donating (+I).
- **CH3 (Methyl group)**: This is also an alkyl group and is electron-donating (+I).
- **C2H5 (Ethyl group)**: This is another alkyl group and is electron-donating (+I).
- **CH (Allyl group)**: This is also an alkyl group and is electron-donating (+I).

4. **Conclusion**:
- Among the given options, the only group that exhibits a -I effect is the **C6H5 (Phenyl group)**.

### Final Answer:
The group that belongs to the -I group is **C6H5 (Phenyl group)**.

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