In which of the following cases can E° be equal to zero?

Question

Quizplus · Accepted Answer

E° can only be zero when the concentrations of reactants and products are equal at standard conditions (1M concentration, 1 atm pressure, 298 K temperature). This only occurs in a reversible reaction where the reactants and products are present in equal amounts at equilibrium. This is true for reaction II only, where H2(g) and Pt(s) are in equilibrium with H+(aq) and H2O(l). In reactions I and III, E° will not be equal to zero since they involve either only reactants (I) or only products (III) at standard conditions.

In Which of the Following Cases Can E° Be Equal