Question

The correct increasing order of heat evolved when $1.0$ mole of each of the following is hydrogenatd completely is
(I)
(II)
(III) $C{H}_2=C=CH-C{H}_2-C{H}_3$
(IV) $C{H}_3-CH=C=CH-C{H}_3$

• 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. $IV$ is more substituted than $III$. Heat of hydrogenation follow the reverse order.