Question

what is the atomic number of an element? the number of neutrons in the nucleus the number of protons in the nucleus the total number of protons and neutrons the number of electrons in the nucleus

Explanation:

The atomic number of an element is defined as the number of protons in the nucleus of an atom of that element. It determines the element's identity. Neutrons are not part of the atomic - number definition, and electrons are outside the nucleus. The total number of protons and neutrons is the mass - number.

Answer:

The number of protons in the nucleus