Mole ratio is the ratio of moles of one substance to the moles of another substance in a balanced equation.
Butane is an organic compound with the formula C4H10 and carbon dioxide is compound (gas) with the formula CO2.
The chemical reaction between butane and carbon dioxide is:
C4H10 + O2 -> CO2 + H2O
It should be balanced:
2C4H10 + 13O2 -> 8CO2 + 10H2O
So, the balanced coefficient of butane is 2, and that of carbon dioxide is 8. According to thid, the mole ratio of butane to carbon dioxide is 2:8 or 1:4.