A characteristic reaction of compounds with a carbon-carbon double bond is an addition reaction. Addition reactions are

Options

A. usually endothermic
B. usually exothermic
C. endothermic or exothermic depending upon the reagent added
D. neither endothermic nor exothermic

Answer

B

Explanation

An addition reaction involves the conversion of one `pi` bond and one `pi` bond and one `sigma` bond into two `sigma` bonds. The evolved in making two `sigma` bonds exceeds that needed to break on `sigma` bond and one `pi` b ond ( beacuse `pi` bonds are weaker). Therefore, addition reactions are usually exothermic.