Answer:
Number of protons
Explanation:
A is false because an atom can have a varying number of electrons and still be the same element, just a different isotope of the element
B is false because the charge of the atom only comes into play when two or more atoms are interacting
C is false bc... well. Hydrogen is literally an element.
D is false because the number of outer shell electrons (valence electrons) just determines what group (or column) the element is in on the periodic table
