Chemistry - GOC Question with Solution | TestHub

A less stable alkene has more potential energy, so it gives out more heat on hydrogenation. Stability rises with the number of alkyl groups on the double bond : (III) is monosubstituted, (I) is disubstituted, (IV) is trisubstituted and (II) is tetrasubstituted. So the heat of hydrogenation order is III $>$ I $>$ IV $>$ II.