At I 127 K and I atm pressures, a gaseous mixture of CO and CO2 in equilibrium with solid carbon has 90.55% CO by mass.C(s)+CO2(g) ⇌ 2CO(g)KC for this reaction at the above temperature is

90.55% CO by mass means 90.55 g CO and 9.45 g CO2 are present in 100 g of mixture.Number of moles of CO,  nCO  = 90.5528=3.234 molNumber of moles of CO2 ,  nCO2= 9.4544=0.215 mol Partial pressure of CO,  PCO= XCO·pXCO=3.2343.234+0.215=0.938PCO= 0.938×1 = 0.938 atmSimilarly, PCO2= XCO2.PXCO2=0.2153.234+0.215=0.062PCO2=0.062×1 =0.062 atmC(s) +CO2(g) ⇌ 2CO(g)Kp=PCO2PCO2=(0.938)20.062= 14.19Δn = 2-1= 1 Kp= KC (RT)Δnor KC=KpRTKC=14.190.0821×1127=0.15336≈0.153