Which of the following will have weakest indicated C-H bond?

Options

A.
B.
C.
D. `CH_(3)-H`

Answer

To determine which of the given options has the weakest indicated C-H bond, we need to analyze the stability of the resulting carbocation formed when the C-H bond breaks. The stability of the carbocation is influenced by the nature of the substituents on the carbon atom.

### Step-by-Step Solution:

1. **Understanding C-H Bond and Carbocation Formation**:
- When a C-H bond breaks, it can lead to the formation of a carbocation (a positively charged carbon species). The stability of this carbocation will influence the strength of the C-H bond.

2. **Identifying the Effects of Substituents**:
- Electron-donating groups (EDGs) stabilize carbocations due to their +I (inductive) effect, while electron-withdrawing groups (EWGs) destabilize them due to their -I effect.
- For example, a methyl group (C-H3) is an EDG, while a nitro group (NO2) is an EWG.

3. **Analyzing Each Option**:
- **Option 1**: If it has an electron-withdrawing group, it will destabilize the carbocation formed, leading to a weaker C-H bond.
- **Option 2**: If it has an electron-donating group, it will stabilize the carbocation, resulting in a stronger C-H bond.
- **Option 3**: If it has a combination of both effects, the overall stability of the carbocation needs to be assessed.

4. **Comparing the Stability of Carbocations**:
- The more stable the carbocation, the stronger the C-H bond. Conversely, the less stable the carbocation, the weaker the C-H bond.
- For example, a tertiary carbocation is more stable than a secondary, which is more stable than a primary.

5. **Conclusion**:
- After analyzing the effects of the substituents on the stability of the carbocation formed from the C-H bond, we can conclude that the option with the strongest electron-withdrawing group will have the weakest C-H bond.

### Final Answer:
The option with the weakest indicated C-H bond is **Option 3**.