Final answer:
Natural gas is the cleanest burning fossil fuel, followed by oil, with coal being the dirtiest due to its higher CO2 emissions.
Step-by-step explanation:
Ranking of Fossil Fuels from Cleanest to Dirtiest
When ranking fossil fuels based on their carbon dioxide emissions, natural gas, oil, and coal are the three main types considered. Natural gas is the cleanest of the fossil fuels, emitting up to 50% less CO2 than coal, hence making it the least polluting. Oil is next in line, being cleaner than coal but dirtier than natural gas. Lastly, coal is the dirtiest form of fossil fuel, emitting about twice as much CO2 per unit of energy compared to other fossil fuels. The transition from coal to natural gas in electricity generation is advocated due to the significant reduction in CO2 emissions it can provide. Therefore, the fossil fuels can be ranked from cleanest to dirtiest for burning as follows: natural gas, oil, and coal.