Question

Five isomeric alkenes (all positional isomers) $A$ to $E$, all on catalytic hydrogenation with $H_2/Pt$ gives the same optically active alkane $F$. Only A and B are optically active and $A$ liberate more heat on hydrogenation than $B.C$ show geometrical isomerism. $E$ evolves more heat on hydrogenation than $D$.

Alkene liberating least heat on hydrogenation is:

• A. $B$
• B. $C$
• C. $D$
• D. $E$

Answer 1

The correct option is C $D$

Higher is the extent of substitution, higher is the stability of alkene and lower is the heat released in the hydrogenation reaction.
D being most substituted releases minimum heat in hydrogenation reaction