Question

an atom of element be has four protons, four electrons, and five neutrons. which element below could be an isotope of this atom? sodium - 20 beryllium - 10 boron - 9 carbon - 9

Explanation:

Isotopes are atoms of the same element with different neutron numbers. The given atom is of element Be (beryllium). So, its isotope must also be beryllium. Among the options, only beryllium - 10 is of the same element (beryllium).

Answer:

beryllium - 10