Given,



The enthalpy of hydrogenation of these compounds will be in the order as:

• A

  $\mathrm{I}>\mathrm{I}\mathrm{I}>\mathrm{I}\mathrm{I}\mathrm{I}$
• Correct answer
  B

  $\mathrm{I}\mathrm{I}\mathrm{I}>\mathrm{I}\mathrm{I}>\mathrm{I}$
• C

  $\mathrm{I}\mathrm{I}>\mathrm{I}\mathrm{I}\mathrm{I}>\mathrm{I}$
• D

  $\mathrm{I}\mathrm{I}>\mathrm{I}>\mathrm{I}\mathrm{I}\mathrm{I}$

Solution

Enthalpy of hydrogenation is inversely proportional to stability of alkene.

Hence, the correct answer is option: 'B'.