Answer: The mole ratio of butane to carbon dioxide is 1 : 4
Step-by-step explanation:
Mole ratio is defined as the ratio of number of moles of the two substances taken into account.
In a chemical reaction, the stoichiometric coefficients represents the number of moles.
For a given chemical equation:

By stoichiometry of the reaction:
2 moles of butane reacts with 13 moles of oxygen to produce 8 moles of carbon dioxide and 10 moles of water.
So, the mole ratio of butane to carbon dioxide in a given chemical reaction is 2 : 8 or 1 : 4