Here's how to determine it:
* Nickel(II) means the nickel ion has a +2 charge (Ni²⁺).
* Nitride refers to the nitrogen anion, which has a -3 charge (N³⁻).
To balance the charges, you need three nickel ions (3 x +2 = +6) and two nitride ions (2 x -3 = -6).
