Which among the following is not an activating group of the benzene ring?

Options

A. `-NH_(2)`
B. `-OCH_(3)`
C. `-Cl`
D. `-CH_(3)`

Answer

To determine which among the given options is not an activating group of the benzene ring, we need to understand what activating groups are and how they affect the reactivity of the benzene ring.

### Step-by-Step Solution:

1. **Identify Activating Groups**: Activating groups are substituents that donate electrons to the benzene ring. This donation increases the electron density of the ring, making it more reactive towards electrophilic substitution reactions.

2. **Common Activating Groups**: Some common activating groups include:
- Amino group (–NH2)
- Alkoxy group (–OCH3)
- Alkyl groups (–CH3, etc.)

3. **Analyze the Given Options**:
- **NH2 Group**: This group has a lone pair of electrons that can be donated to the benzene ring, thus it is an activating group.
- **OCH3 Group**: The methoxy group also has lone pairs that can be donated to the benzene ring, making it an activating group.
- **Cl (Chlorine)**: Although chlorine can participate in resonance due to its lone pairs, it is highly electronegative and withdraws electron density from the benzene ring through the inductive effect. Therefore, it is considered a deactivating group.
- **CH3 Group**: The methyl group can donate electrons through the inductive effect, making it an activating group.

4. **Conclusion**: Among the options provided, the chlorine atom (Cl) is not an activating group of the benzene ring. It is a deactivating group despite being ortho-para directing.

### Final Answer:
**Cl (Chlorine) is not an activating group of the benzene ring.**