How much heat is released per mol of CO2 produced for methane, propane, and ethane?

here is the full question: Natural gas is mostly methane, but also contains some ethane and propane. Enthalpies of combustion for these three gases are -890, -1560, and -2220 kJ/mol, respectively. How much heat is released per mol of CO2 produced for each gas? Based on this analysis, would natural gas or pure... show more here is the full question:
Natural gas is mostly methane, but also contains some ethane and propane. Enthalpies of combustion for these three gases are -890, -1560, and -2220 kJ/mol, respectively. How much heat is released per mol of CO2 produced for each gas? Based on this analysis, would natural gas or pure methane generate less CO2 for the same amount of heat released? Which of natural gas or pure methane generates more energy for the same mass?

i'm mostly looking for some help in figuring out the first question but any insight on the others would be much appreciated
2 answers 2