See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Concept: Carbocation stability depends on hyperconjugation, induction, and resonance. Electron-donating groups (alkyl, lone-pair donors) stabilize carbocations; electron-withdrawing groups destabilize them. Option (a): First ion is CH3-CH(+)-CH3 (secondary carbocation, isopropyl). Second ion is CH3-CH(+)-OCH3. The oxygen lone pairs donate into the empty p-orbital of the adjacent carbocation by resonance, making the second ion MORE stable (oxocarbenium ion). So the first is LESS stable than the second. Option (a) is incorrect. Option (b): First ion is CH3-CH2-CH(+)-CH3 (secondary carbocation, 2-butyl). Second ion is CH2=CH-CH2-CH2(+) (primary allylic carbocation, homoallylic? No — it is CH2=CH-CH2-CH2(+), which is a primary carbocation but NOT directly allylic; the positive charge is on C4 while the double bond is between C1 and C2, so there is no direct resonance stabilization). Wait — re-examining: CH2=CH-CH2-CH2(+): the positive charge is on the terminal carbon, separated from the double bond by one CH2, so it is a homoallylic cation with no direct resonance. Thus the second ion is a primary carbocation with no resonance stabilization. The first ion is a secondary carbocation stabilized by hyperconjugation from two alkyl groups. A secondary carbocation is more stable than a primary non-allylic carbocation. Therefore the first ion IS more stable than the second. Option (b) is correct. Option (c): First ion is cyclohexylmethyl cation (primary, no resonance). Second ion has the double bond in the cyclohexene ring adjacent to the CH2(+), making it an allylic carbocation (resonance-stabilized). So the second is MORE stable. Option (c) is incorrect. Option (d): First ion is a tertiary carbocation (neopentyl-type: C(+) with three carbon substituents). Second ion has nitrogen directly attached to the C(+); nitrogen's lone pair would normally donate, but here the nitrogen already bears a positive charge (quaternary-like environment) — actually the nitrogen is tertiary amine type adjacent to carbocation. The N lone pair can donate into the carbocation making it an iminium-type ion, which is actually MORE stable. So second is more stable. Option (d) is incorrect. Therefore, option (b) is the pair where the first ion (secondary carbocation) is more stable than the second ion (primary, non-allylic carbocation). Therefore, the correct answer is B.