Element X with atomic number 10 and atomic mass 21
Element Z with atomic number 10 and atomic mass 22
Explanation:
Isotopy is the existence of two or more atoms of the same element having the same atomic number but different mass numbers due to the differences in the number of neutrons in their various nuclei.
Isotopes of an element have the same electronic configuration.
They share the same chemical properties
They only differ in their masses.
So, Element X and Z with atomic number 10 which is their number of electrons are isotopes. Their mass number, 21 and 22 differs.
