At standard conditions, N2 + 2O2 ⇌ 2NO2; ΔG° = 100 kJ/mole NO + ½O2 ⇌ 2NO2; ΔG° = -35 kJ/mole The standard free energy of formation of NO in kJ/mole is___________________?
A. 15
B. 30
C. 85
D. 170