Initially, Mass of CNG(CH4)=100gm ∴ Moles of CH4=
100
16
=6.25 moles Mass of O2=208gm ∴ Moles of O2=
208
32
=6.5 moles From reaction you can see, 1 mole of CH4 react with 2 mole of O2 ∴6.25 mole of CH4 react with 6.25×2=12.5 moles of O2 But here only 6.5 moles of O2 present So, O2 will act as limiting reagent. ∴ Produced CO2 will depends on moles of O2. From 2 moles of O21 mole of CO2 ∴ From 6.5 moles of O2