Question

the atomic mass is the number of * protons +electrons neutrons + electrons protons + neutrons protons neutrons

Explanation:

To determine the correct option, we recall the concept of atomic mass. The atomic mass (or atomic weight) of an atom is approximately the sum of the number of protons and neutrons in its nucleus. Electrons have a negligible mass compared to protons and neutrons, so they do not contribute significantly to the atomic mass.

• The first option (protons + electrons) is incorrect because electrons' mass is negligible and not part of the atomic mass calculation.
• The second option (neutrons + electrons) is incorrect for the same reason about electrons, and also neutrons alone plus electrons don't define atomic mass.
• The fourth option (protons) is incorrect because it ignores the mass contribution of neutrons.
• The fifth option (neutrons) is incorrect as it ignores protons.
• The third option (protons + neutrons) matches the definition of atomic mass (approximate, as it accounts for the mass of the nucleus where most of the atom's mass is concentrated).

Answer:

C. protons + neutrons