Question

atomic composition quick check
how is the mass number of an atom calculated? (1 point)
protons plus neutrons
electrons plus neutrons
total number of electrons
total number of protons

Explanation:

The mass number of an atom represents the sum of the number of protons and neutrons in its nucleus. Electrons have negligible mass compared to protons and neutrons and are not included in the mass - number calculation.

Answer:

protons plus neutrons