B the atomic number of nitrogen is 7. what is the mass number of a nitrogen atom with 6 neutrons? express your answer as an integer.

Answer is: the mass number of a nitrogen atom is 13.

Atomic number (Z) is total number of protons and mass number (A) is total number of protons and neutrons in a nucleus:

p⁺ (N) = 7; number of protons in nitrogen atom.

n° (N) = 6; number of neutrons in nitrogen atom.

A (N) = p⁺ (N) + n° (N).

A (N) = 7 + 6.

A (N) = 13.