One litre of CO2 is passed over hot coke. The volume becomes 1.4 litre. The per cent composition of products is:

The reaction equation isCO2​+C⟶2CO IV      IV         2VLet X L of CO2​ gives 2X L of CO.Volume of CO2​ left =1−XTotal volume =1.4LSo, (1−X)+2X=1.41+X=1.4X=0.4LAs CO=2X=2×0.4=0.8LVolume of CO2​ = 1.4−0.8 = 0.6L