Answer:
ISOTOPES
Explanation:
As we know that the atoms of same element with different number of protons is known as ISOTOPES
So here we can say that
[tex]_z^{A_1}X , _z^{A_2}X[/tex]
here in above example the two atoms are same with same atomic number z
but the mass number is different in it
As we know that
mass number = number of proton + number of neutrons
So isotopes must have different number of neutrons present in the nuclei
