Name the endothermic reaction out of the following:

Solution(By Examveda Team)

Option A: Catalytic cracking - Catalytic cracking is a process where large hydrocarbon molecules are broken down into smaller ones using a catalyst. This process is typically exothermic, meaning it releases heat as the molecules are broken apart.

Option B: Hydrocracking - Hydrocracking is a process similar to catalytic cracking, but it involves the addition of hydrogen gas under high temperature and pressure. This process requires the input of external heat energy to drive the cracking process, making it endothermic.

Option C: Dehydrogenation of naphthene to produce aromatic - Dehydrogenation reactions involve the removal of hydrogen atoms from hydrocarbon molecules to produce unsaturated compounds. While these reactions can occur with or without external heat, they are generally considered to be slightly endothermic.

Option D: Catalytic polymerisation - Catalytic polymerization involves the joining together of smaller hydrocarbon molecules to form larger ones, typically under the influence of a catalyst. This process is usually exothermic, as the bonds formed release energy.

Conclusion:
While all the options involve important processes in petroleum refining, the only one classified as endothermic is Option B: Hydrocracking. In hydrocracking, the input of external heat energy is necessary to drive the cracking process. Therefore, the correct answer is Option B.