Which fossil fuel has the least amount of carbon dioxide released in the air each year

The correct answer is - natural gas.

The natural gas is the fossil fuel that releases the least amount of carbon dioxide in the atmosphere. It actually releases very little to none. The reason for that is that the natural gas is a fossil fuel which has the methane as its main ingredient. Even when used, it is not causing some serious pollution, instead the pollution comes from not well managed infrastructure and movement from one place to another of the natural gas. The biggest problem, pollution wise, comes from the leaking of the natural gas, when methane is released into the atmosphere.

Natural gas produces the least amount of CO2 in the air

Explanation:

The amount of CO2 produced when a fuel is burned is a function of the carbon content of the fuel. The heat content, or the amount of energy produced when a fuel is burned, is mainly determined by the carbon (C) and hydrogen (H) content of the fuel. Natural gas emits 50 to 60 percent less carbon dioxide (CO2) when combusted in air as compared to other fossil fuels