객관식An atom of krypton-84 (Kr) has an atomic number of 36. How many neutrons are present in one atom of krypton-84?166views
객관식A diagram shows three atoms, each with 6 protons but different numbers of neutrons. What element is represented by these isotopes?109views
객관식Beryllium has several isotopes. How many neutrons are present in the most abundant isotope of beryllium, Be-9?135views