Carbon is made out of a hydrocarbon elememt made out of Hydrogen and Carbon atoms.
Combustion: When fuel burns in plenty of oxygen and produces Carbon dioxide and Water - This is COMPLETE combustion.
Longer chains of Hydrocarbons are Less Efficient Oils. They have HIGH BPS, LOW volatility, They are THICK (high viscosity) and LOW flammability: Oils burn slower.
Shorter chains of Hydrocarbons are More Efficient Fuels. They have LOW BPS, HIGH volatility, They are runny (low viscosity) and HIGH flammability: Oils burn quicker.
Shorter Chains - more runny - less viscous.
Shorter chains - Lower boiling point.
Shorter chains - more flammable - easy to ignite.
Complete combustion occurs when theres plenty oxygen.
During combustion both carbon and hydrogen are oxidised. (Gain oxgyen)