Calculate Kc for the following reaction. 2NO(g)+O2(g)<-->2NO2(g) when equilibrium is established at 500 Kelvin, there are 0.190 moles of NO2, 2.65*10^-4 moles NO, and 0.606 moles O2 in a volume of 0.759 liters. Please explain the steps so I can understand.