Question

what is most likely true of an atom with a mass of 15 amu?
there are 15 protons.
there are 15 electrons.
the total number of protons and electrons is 15.
the total number of protons and neutrons is 15.

Explanation:

The atomic mass unit (amu) of an atom is approximately equal to the sum of the number of protons and neutrons in its nucleus (mass number). Protons and neutrons contribute to the mass of the atom, while electrons have negligible mass. So, an atom with a mass of 15 amu most likely has a total of 15 protons and neutrons. The number of electrons is equal to protons in a neutral atom but doesn't contribute significantly to mass, so the other options are incorrect.

Answer:

D. The total number of protons and neutrons is 15.