Final answer:
When aqueous solutions of nickel(II) sulfate and calcium iodide are combined, a double displacement reaction occurs. The nickel ions react with the iodide ions to form nickel iodide, while the calcium and sulfate ions remain in solution.
Step-by-step explanation:
When aqueous solutions of nickel(II) sulfate and calcium iodide are combined, a double displacement reaction occurs. The nickel ions (Ni2+) in the nickel(II) sulfate solution react with the iodide ions (I-) in the calcium iodide solution to form nickel iodide (NiI2), which is a solid precipitate. The calcium ions (Ca2+) and sulfate ions (SO42-) remain in solution as they were before the reaction.