Here's how we get that:

* Nickel (II): This tells us that the nickel ion has a +2 charge (Ni²⁺).

* Chloride: This is the chlorine ion, which has a -1 charge (Cl⁻).

* To balance the charges: We need two chloride ions (2 x -1 = -2) to balance the +2 charge of the nickel ion.

Therefore, the formula is NiCl₂.