Question

1. an atom has 12 protons in its nucleus. what does this number represent? a) the mass number of the atom b) the atomic number of the atom c) the number of neutrons in the atom d) the number of valence electrons

Explanation:

The atomic number of an element is defined as the number of protons in the nucleus of an atom. Mass number is protons plus neutrons. Number of neutrons is not given by just proton - count. Valence electrons are outer - shell electrons and not directly determined by proton number alone.

Answer:

B. The atomic number of the atom