Question

An atom having atomic mass number 13 has 7 neutrons. What is the atomic number of the atom?

Answer 1

The mass number (A) is defined as the sum of the number of protons and neutrons present in the nucleus and the atomic number is defined as the number of protons or electrons present in an atom.

Thus A = 13, the number of neutrons is 7 so the number of protons is 6.

Thus the atomic number is 6.