Medium Practice — Set 2 — JEE Main 2027 Chemistry Notes

Quick Recap — Electronic Effects & Intermediate Stability

Carbocation stability: $3^\circ>2^\circ>1^\circ>$ methyl; benzyl/allyl are resonance-stabilised.
Free radicals: $3^\circ>2^\circ>1^\circ$ ; carbanions: stabilised by $-I$ / $-M$ (so $CCl_3^->CH_3^->3^\circ$ ).
Resonance (mesomeric): $+M$ donors ( $-OH$ , $-NH_2$ , $-OR$ , $-X$ lone pairs) enrich ortho/para; $-M$ acceptors ( $-NO_2$ , $-CN$ , $-CHO$ , $-COOH$ ) withdraw.
Hyperconjugation (no-bond resonance): more $\alpha$ -H $\Rightarrow$ greater stability of the cation/alkene.