Final answer:
The correct representation for an anion of the nitrogen isotope 14N is 14N3-, as nitrogen forms an anion by gaining three electrons to reach a stable electron configuration.
Step-by-step explanation:
Among the options given for the anion of the nitrogen isotope 14N, the correct representation is 14N3-. In the periodic table, nitrogen is part of group 15, which means it forms anions by gaining three electrons to achieve a stable electron configuration like the nearest noble gas, neon. Therefore, when a nitrogen atom gains three electrons, it becomes a nitride ion (N³-), with three more electrons than protons and a net charge of 3-.