Which of the following ions is most stable ?

Options

A. `CH_3 CH_2 overset(+ )CH_2`
B. `CH_3 overset(+ )CHCH_2 CH_3`
C. `(CH_3)_3 C^(+)`
D. `(CH_3)_3 overset(+ ) C.CH_2`

Explanation

To determine which of the given ions is the most stable, we need to analyze the stability of the carbocations presented in the options.

### Step-by-Step Solution:

1. **Identify the Types of Carbocations**:
- The first ion is CH3 (methyl cation), which is a primary carbocation because the positively charged carbon is attached to one other carbon atom.
- The second ion is CH3CH (ethyl cation), which is a secondary carbocation because the positively charged carbon is attached to two other carbon atoms.
- The third ion is CH2+ (not a complete structure, but if we consider it as a primary carbocation, it is similar to the first).
- The fourth ion is CH3CH2+ (isopropyl cation), which is a secondary carbocation as it is attached to two other carbon atoms.

2. **Stability Order of Carbocations**:
- The general stability order for carbocations is:
- Tertiary (3°) > Secondary (2°) > Primary (1°) > Methyl (0°).
- This means that tertiary carbocations are the most stable due to the greater number of alkyl groups that can donate electron density to the positively charged carbon, stabilizing the charge.

3. **Evaluate the Given Options**:
- CH3 (Primary) - Least stable.
- CH3CH (Secondary) - More stable than primary.
- CH2+ (Primary) - Similar stability to CH3.
- CH3CH2+ (Secondary) - More stable than primary.

4. **Conclusion**:
- Among the given options, the carbocation with the highest stability is the one with the most alkyl groups attached to the positively charged carbon. Since we have two secondary carbocations (CH3CH and CH3CH2+), they are more stable than the primary carbocations (CH3 and CH2+). However, if we had a tertiary carbocation in the options, it would be the most stable.

### Final Answer:
The most stable ion among the given options is the secondary carbocation (CH3CH or CH3CH2+).