Why are fossil fuels considered a nonrenewable resource

Fossils are usually defined as the remnants of the ancient flora and fauna that were buried millions of years ago, transforming into essential resources. These are considered to be non-renewable resources because it cannot be regenerated in a very short span of time. For the formation of fossils, it takes thousands and millions of years. Some of the non-renewable resources that are formed from the fossils are coal, petroleum, crude oil, and natural gas.

Thus, fossil fuels are considered as non-renewable resources.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.