Isotope of an element differ in their

Answer

The ansewer is Atomic masses

Explanation

Isotopes of an element have a same atomic number but differ in their atomic masses. Atomic number indicates a number of protons and atomic mass indicate the number of neutrons plus proton present in the atom. So atoms with the same number of protons but different number of neutrons are termed as isotopes.

Isotopes of an element will contain the same number of protons and electrons but will differ in the number of neutrons they contain. In other words, isotopes have the same atomic number because they are the sameelement but have a different atomic mass because they contain a different number of neutrons.