Fossil fuel
Oxygen can not burn in air.
Magnesium burns in air to produce Magnesium oxide. Mg + O2 = MgO2.
Charcoal burns quite well as a fuel, it just needs an air supply
gas gas
Yes, that is true
Oxygen in the air reacts with the fuel in a process called combustion to release energy
Natural gas is a fuel because it burns with air to produce heat, which is what fuels do.
carbon dioxide
Just due to the heat of Compression. The fuel is Injected at a point where the air temp is high enough the fuel burns.
water
As fossil fuels are made up of Carbon and Hydrogen. This burns in oxygen (in air) to form Carbon dioxide and Water, so the carbon dioxide is released into the air
An example of a motor that burns fuel without air is a solid fuel rocket motor. These motors contain both fuel and oxidizer within the fuel itself, allowing combustion to occur without the need for external air.