The concept of resonance explains various properties of compounds.The molecules with conjugated system of `pi` bonds, are stabilized by resonace and have low heat of hydrogenation.Hyperconjugative stabilization also decreases heat f hydrogenation.In aromic rings a functional group with a lone pair of electron exerts +m effect. Some functional groups like -NO, -NC, -CH=`CH_2` can function both as electron releasing (+m,+R) or electron withdrawing (-m,-R) groups.More extended conjugation provides more stabilization.
The correct heat of hydrogenation order is
(p)1,3-Pentadiene , (q)1,3-Butadiene , (r)2,3-Dimethyl-1,3-butadiene , (s)Propadiene

Options

A. pgtqgtrgts
B. sgtqgtpgtr
C. qgtsgtpgtr
D. sgtpgtqgtr

Answer

B

Explanation