Based on the reactions:
1. 2NO2 (g)→N204 (g). AH1 = -57.2 kJ
2. 2NO(g) + O2(g) → 2NO2 (g) AH2 = -114.1 kJ
Use Hess's law to calculate AH for:
2NO(g) + O2 (g)→→N2O4 (g)