Question

The correct increasing order of heat evolved when $1.0$ mole of each of the following is hydrogenatd completely is
(I)
(II)
(III) $CH _{2}= C = CH - CH _{2}- CH _{3}$
(IV) $CH _{3}- CH = C = CH - CH _{3}$

• A. I < II < I < III
• B. I < II < IV < III
• C. III < IV < I < II
• D. II < I < IV < III

Answer 1

Answer: (D)

The order of stability of dienes is cumulated $<$ isolated $<$ conjugated.

Also, more substituted diene is more stable than less substituted diene. $I V$ is more substituted than $III$. Heat of hydrogenation follow the reverse order.