AIIMS 2019 Chemistry Carbocation Stability MCQ Question

Option B is correct because carbocation (iii) has the highest stability due to the presence of nine hyperconjugation structures, which effectively delocalize the positive charge. Carbocation (ii) follows with six hyperconjugation structures, providing moderate stability, while carbocation (i) with eight hyperconjugation structures is slightly less stable than (ii). Carbocation (iv), despite exhibiting a +M effect, has the least stability due to the absence of significant hyperconjugation, making it less stable than the others. Thus, the order of stability is iii > ii > i > iv.