Question

How many moles of ethane is required to produce 44 g of CO2 after combustion?

Answer 1

2C2H6(g) + 7O2(g) = 4CO2(g) + 6H2O(g)
But we want only 1 mol of CO2, so dividing the reaction coefficients by 4, we get:
0.5C2H6(g) + 1.75O2(g) = CO2(g) + 1.5H2O(g)
So, 0.5 mol of ethane are required to produce 1 mol of CO2.