Which of the following alkyl groups has the maximum `+I` effect?

Options

A. `(CH_(3))_(2)CH-`
B. `(CH_(3))_(3)C-`
C. `CH_(3)CH_(2^(-))`
D. `CH_(3^(-))`

Explanation

To determine which alkyl group has the maximum +I effect, we need to analyze the structures of the given alkyl groups and their ability to donate electron density through inductive effects. The +I effect refers to the electron-donating ability of alkyl groups.

### Step-by-Step Solution:

1. **Identify the Alkyl Groups**:
Let's assume the alkyl groups are as follows:
- A: CH3- (Methyl group)
- B: C(CH3)3 (Tert-butyl group)
- C: CH2CH3 (Ethyl group)
- D: CH3CH2CH2- (Propyl group)

2. **Draw the Structures**:
- A: CH3 (Methyl)
- B: C(CH3)3 (Tert-butyl)
- C: CH2CH3 (Ethyl)
- D: CH3CH2CH2 (Propyl)

3. **Analyze the Electron-Donating Ability**:
- **Methyl Group (A)**: The methyl group can donate one electron density.
- **Tert-butyl Group (B)**: The tert-butyl group has three methyl groups attached to a central carbon. Each methyl group donates electron density, resulting in a strong +I effect.
- **Ethyl Group (C)**: The ethyl group has two carbons, but only one of them is a methyl group, so it has a lesser +I effect compared to tert-butyl.
- **Propyl Group (D)**: Similar to the ethyl group, the propyl group has only one methyl group contributing to the +I effect.

4. **Rank the Alkyl Groups**:
- B (Tert-butyl) has the maximum +I effect due to three methyl groups donating electron density.
- A (Methyl) follows next with one methyl group.
- C (Ethyl) and D (Propyl) have similar effects but are less than A.

5. **Conclusion**:
The alkyl group with the maximum +I effect is **B (Tert-butyl)**, followed by A (Methyl), C (Ethyl), and D (Propyl).

### Final Order:
1. B (Tert-butyl)
2. A (Methyl)
3. C (Ethyl)
4. D (Propyl)