J.R. S. answered 05/17/19
Ph.D. University Professor with 10+ years Tutoring Experience
Cathode (reduction): O2 + 4H+ + 4e- ==> 2H20 Eº = +1.229 V (reduction potential)
Anode (oxidation): NO + 2H2O ==> NO3- + 4H+ + 3e- Eº = +0.958 V (reduction potential)
Multiply reduction rxn by 3 and oxidation rxn by 4 and cancel like items on opposites sides to get...
3O2 + 4NO + 2H2O ==> 4NO3- + 4H+ Eº = 1.229 V - 0.958 V = 0.271 V