Which among the following group when attached to benzene ring will direct the incoming electrophile predominantly to the meta position ?
I. `-CH_(3)`
II. `-CH_(2)Cl`
III. `-NH_(3)^(+)`
IV . `-C Cl_(3)`
`-NHCOCH_(3)`

Options

A. III only
B. I,II and V
C. III and V only
D. III and IV only

Explanation

To determine which substituents direct electrophilic substitution predominantly to the meta position on a benzene ring, we will analyze each of the given substituents one by one.

### Step-by-Step Solution:

1. **Identify the Groups**: The groups provided are:
- I. `-CH₃`
- II. `-CH₂Cl`
- III. `-NH₃⁺`
- IV. `-CCl₃`
- V. `-NHCOCH₃`

2. **Analyze Group I: `-CH₃`**:
- The `-CH₃` group is an electron-donating group due to its +I effect (inductive effect) and hyperconjugation.
- It increases electron density at the ortho and para positions.
- **Conclusion**: Directs to ortho and para positions, **not meta**.

3. **Analyze Group II: `-CH₂Cl`**:
- The `-CH₂Cl` group has a chlorine atom which is an electron-withdrawing group due to its -I effect.
- However, it does not stabilize the positive charge at the meta position effectively, so it also directs electrophiles to ortho and para positions.
- **Conclusion**: Directs to ortho and para positions, **not meta**.

4. **Analyze Group III: `-NH₃⁺`**:
- The `-NH₃⁺` group is positively charged and is highly electronegative.
- It pulls electron density towards itself, creating a deficiency at the ortho and para positions.
- **Conclusion**: Directs to meta position.

5. **Analyze Group IV: `-CCl₃`**:
- The `-CCl₃` group is a strong electron-withdrawing group due to the presence of three chlorine atoms.
- It also directs electrophiles to the meta position as it destabilizes the positive charge at the ortho and para positions.
- **Conclusion**: Directs to meta position.

6. **Analyze Group V: `-NHCOCH₃`**:
- The `-NHCOCH₃` group has a nitrogen atom that can donate electron density, but the carbonyl (C=O) is an electron-withdrawing group.
- The overall effect is that it directs electrophiles to the ortho and para positions.
- **Conclusion**: Directs to ortho and para positions, **not meta**.

### Final Answer:
The groups that direct electrophiles predominantly to the meta position are:
- III. `-NH₃⁺`
- IV. `-CCl₃`