Which of the following group shows `+I` effects?

Options

A. `-Br`
B. `-COOH`
C. `-OR`
D. `-COO-`

Answer

To determine which of the following groups shows a +I (positive inductive) effect, we need to analyze the groups provided in the question. The +I effect refers to the electron-donating ability of a substituent through the sigma bond, which generally occurs with groups that are less electronegative than carbon.

### Step-by-Step Solution:

1. **Identify the Groups:**
We have four groups to analyze: A (Br), B (COOH), C (OR), and D (C=O with a negative charge on O).

2. **Analyze Group A (Br):**
- Bromine (Br) is a halogen and is more electronegative than carbon.
- Therefore, it pulls electron density towards itself, showing a -I effect.
- **Conclusion:** Group A does not show +I effect.

3. **Analyze Group B (COOH):**
- The carboxylic acid group (COOH) has a carbonyl (C=O) and hydroxyl (OH) group.
- The electronegative oxygen atoms pull electron density away from the carbon, leading to a -I effect.
- **Conclusion:** Group B does not show +I effect.

4. **Analyze Group C (OR):**
- The OR group (alkoxy group) has an oxygen atom that is electronegative.
- It pulls electron density towards itself, resulting in a -I effect.
- **Conclusion:** Group C does not show +I effect.

5. **Analyze Group D (C=O with a negative charge on O):**
- In this case, the oxygen has a negative charge, which can donate electron density to the carbon through resonance.
- This results in an increase in electron density on the carbon atom, indicating a +I effect.
- **Conclusion:** Group D shows +I effect.

### Final Answer:
The group that shows a +I effect is **Group D**.