Which statement is most useful in explaining why chemists assign atoms to chemical elements by counting protons? a. the proton's negative charge holds electrons in the atom. b. the nucleus doesn't change in stable isotopes. c. protons at the atom's surface determine the atom's behavior. d. 99% of the atom's mass consists of protons. e. none of these. elements are defined by the number of protons.

Answer;

E. None of these. Elements are defined by the number of protons.

Explanation;Protons contribute to the mass of an atom and provide the positive charge to the nucleus. The number of protons also determines the identity of the element.Each element has a unique number of protons. An element's atomic number is equal to the number of protons in the nuclei of any of its atoms.The number of electrons on the other hand determines the chemical properties of the atom.