Problem- Given that the partial pressure of O2 in the atmosphere is 0.20 atm and the concentration of H3O+ is 2.0 x 10-6 M, determine the half-cell potential for the reduction of O2 according to the reaction-
O2 + 4 H3O+ + 4e- ---> 6 H2O E° = 1.229 V
Answer all three questions and provide required steps