Which of the following species acts as reducing agent during working of hydrogen-oxygen fuel cell?

Step-by-step solution

Hydrogen-oxygen fuel cells operate through redox reactions where hydrogen serves as the reducing agent. At the anode, hydrogen undergoes oxidation: H ₂(g) 2 H ^+(aq) + 2e^- in acidic medium H ₂(g) + 2 OH ^-(aq) 2 H ₂ O (l) + 2e^- in alkaline medium At the cathode, oxygen undergoes reduction: O ₂(g) + 4 H ^+(aq) + 4e^- 2 H ₂ O (l) in acidic medium O ₂(g) + 2 H ₂ O (l) + 4e^- 4 OH ^-(aq) in alkaline medium Since hydrogen loses electrons in both acidic and alkaline environments, it functions as the reducing agent thro