The nitride ion has   protons and   electrons.Which equation can be used to find the charge of the ion?

The charge of an ion can be determined by the equation:

Charge = Number of protons - Number of electrons

This equation is based on the fact that protons carry a positive charge and electrons carry a negative charge. If an atom gains or loses electrons, it becomes an ion with a net charge. If the number of protons and electrons are equal, the atom is neutral. If there are more protons than electrons, the ion has a positive charge. If there are more electrons than protons, the ion has a negative charge.