What is the atomic mass of Carbon?

The atomic mass of carbon is 12 because it is the weighted average of the masses of its naturally occurring isotopes. Carbon has three isotopes: carbon-12, carbon-13, and carbon-14. The most abundant isotope, carbon-12, has a mass of exactly 12 atomic mass units (amu). Carbon-13 has a slightly higher mass, while carbon-14 has a higher mass due to its two extra neutrons. As the atomic mass is calculated based on the relative abundance of each isotope, and carbon-12 is the most abundant, the average atomic mass of carbon is rounded to 12 amu.