Question

The correct order for the increasing heat of hydrogenation for the following structures is :

• A. $\left(a\right)<\left(b\right)<\left(c\right)$
• B. $\left(b\right)<\left(c\right)<\left(a\right)$
• C. $\left(c\right)<\left(b\right)<\left(a\right)$
• D. $\left(a\right)<\left(c\right)<\left(b\right)$

Answer 1

The correct option is A $\left(a\right)<\left(b\right)<\left(c\right)$



(a) has 10 alpha hydrogens.
(b) has 6 alpha hydrogens.
(c) has 3 alpha hydrogens.

More the number of alpha hydrogens more is the stability and lesser is the heat of hydrogenation.
So the correct order of increase in heat of hydrogenation is $\left(a\right)<\left(b\right)<\left(c\right)$