In a hydrogen-oxygen fuel cell, what is the half-equation occurring at the positive electrode?

In a hydrogen-oxygen fuel cell, the positive electrode is where the reduction half-reaction occurs, which in this case involves the reaction of oxygen and hydroxide ions. The correct half-equation describes the consumption of hydroxide ions and generates water while releasing electrons.

The reaction can be broken down as follows: oxygen molecules (O2) react with hydroxide ions (OH-) to produce water (H2O) and electrons. The overall process indicates that oxygen is being reduced, as it gains the electrons produced from the oxidation of hydrogen at the negative electrode (anode). The release of electrons in this half-equation signifies the essential role of the positive electrode in maintaining the electrical flow and facilitating the electrochemical reaction.

This choice captures the essence of the electrochemical processes in a fuel cell, particularly the reaction at the positive electrode where the reduction of oxygen occurs. The other options do not correctly represent the reaction that takes place at the positive electrode in a hydrogen-oxygen fuel cell.