JEE Main · 2026 · 05 Apr 2026 · Shift 2 · General Organic Chemistry

Alkene stability rises with the number of alkyl groups attached to the doubly bonded carbons, because the $+\mathrm{I}$ effect and hyperconjugation of these groups stabilise the $\pi$ system; the number of $\alpha$-hydrogens available for hyperconjugation measures this. 2,3-Dimethylbut-2-ene is tetrasubstituted and offers the largest set of $\alpha$-hydrogens, 2-methylbut-2-ene is trisubstituted, cis-but-2-ene is disubstituted, and prop-1-ene is only monosubstituted. The stability therefore decreases in the order 2,3-dimethylbut-2-ene $>$ 2-methylbut-2-ene $>$ cis-but-2-ene $>$ prop-1-ene, that is C $>$ A $>$ B $>$ D.