What is the atomic mass of a carbon isotope that has 6 protons and 7 neutrons?

The atomic mass of a carbon isotope that has 6 protons and 7 neutrons is 13

Explanation:

Remember that whilst the atomic number represents the number of protons in an atom, the mass number represents the summation of protons and neutrons particles in the atomic nuclei. Therefore, in this case, the carbon will have a mass number of;

6 +  7 = 13

Isotopes of an element usually have the same atomic number but different mass numbers -because they have slightly different numbers of neutrons. An example is isotopes of Carbon; C-14 and C-12