Question

The atomic mass of carbon-13 is 13. It has six protons. How many neutrons does this isotope have?

Answer 1

The isotope has 7 neutrons. 

Answer 2

carbon dating done with the isotope of carbon with atomic mass 14. No. of protons will not change. so the change will be in no. of neutrons. So the no. of neutrons in isotope of carbon is 8