Which of the following is the correct chemical formula for nickel(II) iodide?

• A. NiI
• B. Ni2I3
• C. NiI2
• D. Ni2I

Answer: (C)

Verified step by step guidance

1. Identify the charge on the nickel ion in nickel(II) iodide. The (II) indicates that nickel has a +2 charge, so the ion is Ni^{2+}.
2. Determine the charge on the iodide ion. Iodide is a halide ion with a charge of -1, so the ion is I^{-}.
3. To write the correct formula, balance the total positive and negative charges so the compound is electrically neutral.
4. Since Ni^{2+} has a +2 charge and I^{-} has a -1 charge, you need two iodide ions to balance one nickel ion.
5. Combine the ions accordingly to get the formula NiI_{2}, which shows one nickel ion combined with two iodide ions.