Question

What kind of cells have positive cell potentials, and all the reduction reactions are reversible?

Answer 1

galvanic cells

Galvanic cells have positive cell potentials, and all the reduction reactions are reversible. The reaction at the anode will be the half-reaction with the smaller or more negative standard reduction potential. Reversing the reaction at the anode  to show the oxidation  but not its standard reduction potential gives: Anode  oxidation :.