Arrange in decreasing order of heat of hydrogenation (to the corresponding alkane): ethene, propene, but-2-ene, 2,3-dimethylbut-2-ene.

Apropene > ethene > but-2-ene > 2,3-dimethylbut-2-ene
B2,3-dimethylbut-2-ene > but-2-ene > propene > ethene
Cethene > but-2-ene > propene > 2,3-dimethylbut-2-ene
Dethene > propene > but-2-ene > 2,3-dimethylbut-2-ene

Answer: D

Alkene stability rises with the number of alpha hydrogens (hyperconjugation): 0, 3, 6 and 12 for the four alkenes. The more stable the alkene, the smaller the heat released on hydrogenation. So heat of hydrogenation falls in the order given in the key.

Practice General Organic Chemistry I: Electronic Effects More on Hyperconjugation

Previous questionNext question

More questions on Hyperconjugation

In which of the following can hyperconjugation operate? JEE Main level
2,3-Dimethylbut-2-ene, (CH3)2C=C(CH3)2, is protonated at one sp2 carbon to give the more stable carbocation. The number of hyperconjugative ... JEE Advanced level
Consider the alkenes (I) CH3CH=CHCH3, (II) (CH3)2C=CHCH3, (III) (CH3)2C=C(CH3)2 and (IV) (CH3)2C=CH2. The correct order of the number of hyp... JEE Advanced level
The 3-methylbutan-2-yl cation, (CH3)2CH-CH+-CH3, rearranges by a 1,2-hydride shift to a more stable carbocation. The number of alpha C-H bon... JEE Advanced level
The correct order of stability of the carbocations (I) p-CH3O-C6H4-CH2+, (II) p-CH3-C6H4-CH2+, (III) C6H5-CH2+ and (IV) p-O2N-C6H4-CH2+ is JEE Advanced level
The correct order of acid strength of benzoic acid (I), 4-methylbenzoic acid (II) and 4-nitrobenzoic acid (III) is JEE Advanced level