ANS:B - H₂

Naphtha in a fertilizer plant is typically used as a source of hydrogen (H2). In the context of fertilizer production, naphtha is often utilized as a feedstock for steam reforming processes to produce hydrogen gas (H2). This hydrogen is an essential component in various chemical reactions involved in ammonia synthesis and other fertilizer manufacturing processes. Steam reforming of naphtha involves the reaction of naphtha (a mixture of hydrocarbons) with steam (H2O) at high temperatures in the presence of a catalyst, resulting in the production of hydrogen gas and carbon monoxide. The hydrogen gas generated in this process is then used in downstream processes, such as ammonia synthesis, where it serves as a key reactant. So, the correct answer is: H2