The isotopic pairs out of the following ₈C¹⁶, ₆C¹⁴, ₇N¹⁴, ₈O¹⁸, ₇N¹⁶ are:

₈C¹⁶ and ₈O¹⁸ also ₇N¹⁴ and ₇N¹⁶. These are the only pairs in the given elements which are isotopic.

Isotopes have the same number of proton and different number of neutrons, in all the pairs the protons are the same but the atomic masses are different.