What is the correct order of exothermicity for hydrogenation of the following hexadienes upon treatment with H₂/Pd (more exothermic less exothermic)?

Question

What is the correct order of exothermicity for hydrogenation of the following hexadienes upon treatment with H₂/Pd (more exothermic > less exothermic)?

Quizplus · Accepted Answer

The hydrogenation of a hexadiene results in the formation of a hexene. The degree of exothermicity of the process depends on the substitution pattern of the hexadiene. 
In the given options, the correct order of exothermicity for hydrogenation of the hexadienes is 3 > 1 > 2. This is because hexadiene 3 has the most substituents, and hence, the most stable double bonds, resulting in the least exothermic hydrogenation. On the other hand, hexadiene 2 has the least substituents, and hence, the least stable double bonds, resulting in the most exothermic hydrogenation.

What Is the Correct Order of Exothermicity for Hydrogenation of the Following