Hydrocarbons are mostly C by mass. Carbon dioxide is 27% C, 73% O (one C atom to two O atoms). So the output of one ton of hydrocarbons (coal, gasoline, paraffi

Hydrocarbons are mostly C by mass. Carbon dioxide is 27% C, 73% O (one C atom to two O atoms). So the output of one ton of hydrocarbons (coal, gasoline, paraffin, it doesn't matter) is three tons of CO2. Some of the rest of the 14 parts air goes to burning the H atoms, which don't weigh much, and producing water. Most of it is nitrogen which isn't burned.