Which of the following are correct ?

Options

A. `CH_3-O-CH_2^(o+)` is more stable than `CH_3-CH_2^(o+)`
B. `(CH_3)_2CH^(o+)` is less stable than `CH_3-CH_2-CH_2^(o+)`
C. `CH_2=CH-CH_2^(o+)` is more stable than `CH_3-CH_2-CH_2^(o+)`
D. `CH_2=CH^(o+)` is more stable than `CH_3-CH_2^(o+)`

Explanation

To determine which statements regarding carbocation stability are correct, we can analyze the concepts of stability in carbocations, including the effects of mesomeric, hyperconjugation, inductive, and resonance effects.

### Step-by-Step Solution:

1. **Understanding Carbocation Stability**:
- Carbocations are positively charged carbon species. Their stability is influenced by the surrounding groups and the type of bonds they form. The more stable a carbocation is, the more readily it can exist.

2. **Evaluating Aromaticity**:
- The first point mentions aromaticity. Aromatic compounds are cyclic, planar, and follow Huckel's rule (4n + 2 π electrons). Since carbocations are not inherently aromatic, this point is **false**.

3. **Mesomeric Effect**:
- The second point discusses the mesomeric effect, which involves the delocalization of electrons. Carbocations can be stabilized by adjacent double bonds or lone pairs that can donate electron density. Thus, this point is **true**.

4. **Inductive and Hyperconjugation Effects**:
- The next points involve inductive effects (electron-withdrawing or donating effects through sigma bonds) and hyperconjugation (stabilization due to the overlap of σ-bonds with an empty p-orbital).
- Comparing two carbocations, one with more alkyl groups (which can donate electron density through hyperconjugation) will be more stable than one with fewer alkyl groups. Therefore, if we have CH3^+ vs. CH2^+CH3, the CH3^+ is less stable due to less hyperconjugation. This point is **false**.

5. **Comparing SP2 and SP3 Hybridization**:
- The stability of carbocations also depends on hybridization. SP2 hybridized carbocations (like those with double bonds) are generally more stable than SP3 hybridized ones. If the statement indicates that SP2 carbocations are less stable than SP3, it is **false**.

6. **Conclusion**:
- Based on the analysis, the correct statements are those related to mesomeric effects and the general understanding of carbocation stability. The statements regarding aromaticity, hyperconjugation, and hybridization comparisons are incorrect.

### Final Answer:
- The correct statements are related to the mesomeric effect and the general stability of carbocations. Therefore, options regarding mesomeric effects are **true**, while those regarding aromaticity and hybridization comparisons are **false**.