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Given
The enthalpy of hydrogenation of these compounds will be in the order as:
The enthalpy of hydrogenation of these compounds will be in the order as:
A
I > II > III
B
III > II > I
C
II > III > I
D
II > I > III
Detailed Solution
Enthalpy of hydrogenation $\propto \frac{1}{\text{stability}}$ (each compound takes up the same number of $H_2$).
I (mesitylene) is aromatic and most stable; II has two conjugated ring double bonds; III has three isolated exocyclic double bonds and is least stable.
So the enthalpy of hydrogenation is III > II > I.
I (mesitylene) is aromatic and most stable; II has two conjugated ring double bonds; III has three isolated exocyclic double bonds and is least stable.
So the enthalpy of hydrogenation is III > II > I.