What information about these isotopes is needed to determine bromine’s average atomic mass? Choose 2 answers: Choose 2 answers: (Choice A) the number of electrons in each isotope A the number of electrons in each isotope (Choice B) the atomic number of each isotope B the atomic number of each isotope (Choice C) the atomic mass of each isotope C the atomic mass of each isotope (Choice D) the relative abundance of each isotope D the relative abundance of each isotope