The formula of the compound formed between Zn²⁺ ions and Cl⁻ ions is ZnCl2.
Explanation: Zinc (Zn) typically has a +2 oxidation state, meaning it loses two electrons to form Zn²⁺. Chlorine (Cl) has a -1 oxidation state and forms Cl⁻ ions when it gains an electron. To balance the charges in the compound, two chloride ions are needed to balance the charge of one zinc ion. Therefore, the chemical formula is created by combining one zinc ion with two chloride ions, resulting in ZnCl2.