Some pairs of ions are given below. In which pair, first ion is more stable than second ?

Options

A. `CH_(3)-overset(o+)CH-CH_(3) and CH_(3) -overset(o+)CH-OCH_(3)`
B. `CH_(3)-CH_(2)-overset(o+)CH-CH_(3)and CH_(2)=CH-CH_(2)-overset(o+)CH_(2)`
C.
D.

Explanation

To determine which pair of ions has the first ion more stable than the second, we will analyze each pair based on the principles of stability, such as hyperconjugation, resonance, and inductive effects.

### Step-by-Step Solution:

1. **Analyze the First Pair:**
- **Ions:** CH3CH+CH3 (A) and CH3CH+OCH3 (B)
- **Stability Factors:**
- Ion A has no groups that can stabilize the positive charge.
- Ion B has an OCH3 group, which is a +M (mesomeric) group that can donate electron density through resonance, stabilizing the carbocation.
- **Conclusion:** Ion B is more stable than Ion A.

2. **Analyze the Second Pair:**
- **Ions:** CH3CH2CH+ (C) and CH2=CHCH2+ (D)
- **Stability Factors:**
- Ion C can undergo hyperconjugation with three hydrogens, leading to more hyperconjugative structures.
- Ion D has only two hydrogens available for hyperconjugation.
- **Conclusion:** Ion C is more stable than Ion D.

3. **Analyze the Third Pair:**
- **Ions:** CH2+ (E) and CH2=CH+ (F)
- **Stability Factors:**
- Ion E has no resonance stabilization.
- Ion F can stabilize the positive charge through resonance with the double bond.
- **Conclusion:** Ion F is more stable than Ion E.

4. **Analyze the Fourth Pair:**
- **Ions:** CH2CH3C+H (G) and CH3C+H (H)
- **Stability Factors:**
- Ion G can stabilize the positive charge through hyperconjugation with multiple hydrogens.
- Ion H has fewer hydrogens available for hyperconjugation.
- **Conclusion:** Ion G is more stable than Ion H.

### Final Conclusion:
The only pair where the first ion is more stable than the second is the **second pair (C and D)**, where CH3CH2CH+ (C) is more stable than CH2=CHCH2+ (D).