Chemistry - GOC Question with Solution | TestHub

A less stable alkene gives out more heat. Stability rises with the number of alkyl groups on the $\mathrm{C}=\mathrm{C}$ : (II) is disubstituted, (I) is trisubstituted and (III) is tetrasubstituted. So the order of heat of hydrogenation is II $>$ I $>$ III.