Question

What are the stable isotopes of carbon?

Answer 1

Carbon-12 and carbon-13 are the only two stable isotopes of carbon. Carbon-14 is not stable but is continually regenerated, so we see it in nature.

Explanation:

There are many isotopes of carbon, most of them shntheric and highly unstable. A complete list is given at https://en.wikipedia.org/wiki/Isotopes_of_carbon.

Both stable isotopes of carbon occur in nature, carbon-12 being the overwhelming majority and carbon-13 being almost all the rest.

Carbon-14 accounts for just one part per trillion of naturally occurring carbon, but we can detect its radiation. This radioactive isotope "should be" long gone but is continually regenerated by the action of cosmic rays (https://en.wikipedia.org/wiki/Cosmogenic_nuclide).