A vessel at 1000 K contains CO2 with a pressure of 0.5 atm. Some of CO2 is converted into CO on addition of graphite. The value of K at 1000 K, when total pressure equilibrium is 0.8atm will be

CO2(g)+C(s)⇌2CO(g)Initial          0.5                    0At equil. (0.5 - x)                2xTotal pressure = 0.5 - x + 2x = 0.5 + x⇒0.5+x= 0.8⇒x= 0.8-0.5= 0.3atmpco=2x  = 2×0.3= 0.6 atmK=pco2pco2=(0.6)2(0.5-0.3)(0.6)20.2=1.8 atm