Question

The mass number of an atom is equal to the number of ____ in its nucleus.

Answer 1

Nucleons:

1. The protons and neutrons present in the nucleus of an atom are together called nucleons.
2. The mass number of the atom is equal to the number of nucleons present in the nucleus of the atom.
3. For example, the atomic number of lithium is 3.
4. It contains three protons and four neutrons.
5. Hence, the atomic mass of lithium is 7.

Hence, the mass number of an atom is equal to the number of nucleons in its nucleus.