Question

q 5. the mass number of an atom is the sum of: neutrons only, protons only, neutrons + protons, electrons + protons

Explanation:

The mass number of an atom is calculated by adding the number of protons and neutrons. Protons and neutrons are found in the nucleus and have significant mass compared to electrons, whose mass is negligible in calculating the mass - number.

Answer:

C. Neutrons + protons