NEET2026ChemistryChapterActual
Arrange the following carbocations in the increasing order of their stability: (I) CH ₂= CH - + C H ₂ (II) CH ₃- O - + C H ₂ (III) CH ₃- + C H ₂ (IV) NO ₂- + C H ₂
Options
- A(IV) < (III) < (II) < (I)
- B(IV) < (III) < (I) < (II)
- C(II) < (I) < (III) < (IV)
- D(III) < (IV) < (I) < (II)
Correct answer
B. (IV) < (III) < (I) < (II)
Step-by-step solution
The stability of carbocations is determined by the electronic effects of the attached groups. In (IV), the NO ₂ group exerts a strong - I and - M effect, which highly destabilizes the positive charge. Thus, it is the least stable. In (III), the ethyl carbocation is stabilized by the + I effect and hyperconjugation from the three -hydrogens of the methyl group. In (I), the allyl carbocation is stabilized by resonance with the adjacent bond. Resonance stabilization is generally more effective than hyperconjugation, m