AIIMS 2018 Chemistry Inductive and Resonance Effects MCQ Question
The figure (i) has less stable conjugate base, the figure (ii) has equally stable resonating structure, the figure (iii) has –I effect and figure (iv) has +I effect as shown below.
i > ii > iii > iv
iii > ii > i > iv
ii > iii > iv > i
iv > iii > ii > i
Correct Answer
Detailed Explanation
Option A is correct because it ranks the stability of conjugate bases based on their resonance and inductive effects: figure (i) has a less stable conjugate base due to poor resonance stabilization, while figure (ii) has equally stable resonating structures that enhance stability. Figure (iii) exhibits a –I (inductive) effect, which destabilizes the conjugate base, while figure (iv) shows a +I effect that also contributes to destabilization, but to a lesser extent than the –I effect. Other options incorrectly rank the stability by not adequately considering the relative strengths of resonance and inductive effects in determining the stability of the conjugate bases.
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