Knowing that, the number of protons should be obvious, and then you can calculate the number of neutrons.

All carbon atoms have 6 protons. (You can find this information on the periodic table). The mass number is the sum of the number of protons in an atom and the number of neutrons in an atom. So 6 protons + 6 neutrons = 12

the mass number is 12

so what plus what =’s 12

6 and 6

so there is 6 protons and 6 neutrons

neutrons=mass no.- no. of protons

= 12-6

=6

The number of neutrons that it has is the atomic mass-the atomic number.

I believe C is 6. With mass 12 that means it has 6 of each.

I have not been in school since i graduated in 2006, sort of forget. going to college soon.