What does an atomic number represent in an atom? number of neutrons number of protons number of electrons number of protons and neutrons

The number of protons in the nucleus of the atom is equal to the atomic number (Z). The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus.

I'm pretty sure the answer is Number of Protons

Explanation:

I took the k-12 test

its first and third is your answer i did the qustion the fourth isnt right

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