Find the standard reduction potentials for the following half reactions in acidic solution.
a.) E° for MnO4 (aq) + 8 H+ (aq) + 5e^- -> Mn^2+ (aq) + 4 H2O (I)
b.) E° for NO3 (aq) + 4H^+ (aq) + 3e^- ----> NO (g) + 2 H2O (I)
c.) E° for O2 (g) + 4H^+ (aq) + 4 e^- ----> 2 H2O (I)