The correct option is
C 7 : 11
The molar masses of
C,
O2,
CO and
CO2 are 12 g/mol, 32 g/mol, 28 g/mol and 44 g/mol respectively.
Let 100 g of C and 200 g of O2 are present which corresponds to 8.33 moles of C and 6.25 moles of O2.
Let x moles of C react with x moles of O2 to form x moles of CO2.
8.33−x moles of C will react with 8.33−x2 moles of O2 to form 8.33−x moles of CO.
But, 8.33−x2 moles of O2 is also equal to 6.25−x moles.
Hence, 8.33−x2=6.25−x or x=4.17.
The number of moles of CO formed is 8.33−x=4.16 and the number of moles of CO2 formed is x=4.17.
Thus, equal number of moles of CO and CO2 is formed.
Hence, the ratio of the weight percent of CO and CO2 is equal to the ratio of their molar masses which is 28:44 or 7:11.