Final answer:
The molar ratio between carbon dioxide and water is 4:5.
Step-by-step explanation:
The molar ratio between carbon dioxide (CO2) and water (H2O) can be determined from the balanced chemical equation you provided:
2 C4H10 + 13 O2 = 8 CO2 + 10 H2O
According to this equation, for every 8 moles of CO2 produced, 10 moles of H2O are produced. Therefore, the molar ratio between CO2 and H2O is 8:10, or simplified, 4:5.