JEE Main 2026 — Hydrocarbons Question with Solution

The stability of alkenes is directly proportional to the number of $\alpha$-hydrogen atoms due to hyperconjugation.

Let us count the number of $\alpha$-hydrogen atoms in each given alkene:

A. 2-Methylbut-2-ene: $(C{H}_3{)}_{2}C=CHC{H}_3$
Number of $\alpha$-hydrogen atoms = $3+3+3=9$

B. cis-But-2-ene: $C{H}_{3}CH=CHC{H}_3$
Number of $\alpha$-hydrogen atoms = $3+3=6$

C. 2,3-Dimethylbut-2-ene: $(C{H}_3{)}_{2}C=C(C{H}_3{)}_2$
Number of $\alpha$-hydrogen atoms = $3+3+3+3=12$

D. Prop-1-ene: $C{H}_{3}CH=C{H}_2$
Number of $\alpha$-hydrogen atoms = $3$

Since the stability of an alkene increases with the number of $\alpha$-hydrogen atoms, the correct stability order is C > A > B > D.

Answer: C > A > B > D