Question

Which of the following process is (are exothermic)?

• A. All of these
• B. (I) and (II) only
• C. (III) and (IV) only
• D. (I), (III) and (IV) only

Answer 1

The correct option is C (III) and (IV) only

In reactions (III) and (IV), alkenes rearrange to form more substituted alkenes.
More substituted alkenes are more stable than less substituted alkenes. They have lower enthalpy than less substituted alkenes.
Hence, in reactions (III) and (IV), the enthalpy of reactants is higher than the enthalpy of products. These reactions are exothermic.