Chemistry - GOC Question with Solution | TestHub

The stability of carbocations is primarily determined by resonance, followed by hyperconjugation and inductive effects. Carbocation III (benzyl) is stabilized by extensive resonance over the benzene ring, providing multiple resonance structures. Carbocation I (allylic) is also resonance-stabilized but has fewer resonance structures than III. Carbocation II (primary propyl) is only stabilized by the positive inductive effect and hyperconjugation from the adjacent ethyl group. Resonance stabilization is significantly more effective than hyperconjugation, making III and I much more stable than II. Therefore, the correct order of stability is $\mathbf{III}>\mathbf{I}>\mathbf{II}$.