Which of the following is the balanced complete ionic equation for the reaction: CaS(aq) + NiCl2(aq) → NiS(s) + CaCl2(aq)?

• A. Ca^2+(aq) + S^2-(aq) + Ni^2+(aq) + 2Cl^-(aq) → Ni^2+(aq) + S^2-(aq) + CaCl2(aq)
• B. Ca^2+(aq) + Ni^2+(aq) + 2Cl^-(aq) → NiS(s) + Ca^2+(aq) + 2Cl^-(aq)
• C. CaS(aq) + Ni^2+(aq) + 2Cl^-(aq) → NiS(s) + Ca^2+(aq) + 2Cl^-(aq)
• D. Ca^2+(aq) + S^2-(aq) + Ni^2+(aq) + 2Cl^-(aq) → NiS(s) + Ca^2+(aq) + 2Cl^-(aq)

Answer: (D)

Verified step by step guidance

1. Identify the compounds involved in the reaction: CaS(aq), NiCl2(aq), NiS(s), and CaCl2(aq).
2. Write the dissociation of each aqueous compound into its ions: CaS(aq) dissociates into Ca^2+(aq) and S^2-(aq); NiCl2(aq) dissociates into Ni^2+(aq) and 2Cl^-(aq).
3. Recognize that NiS(s) is a solid and does not dissociate into ions, while CaCl2(aq) dissociates into Ca^2+(aq) and 2Cl^-(aq).
4. Combine all the ions from the reactants side: Ca^2+(aq) + S^2-(aq) + Ni^2+(aq) + 2Cl^-(aq).
5. Write the complete ionic equation by showing the formation of the solid NiS(s) and the remaining ions: NiS(s) + Ca^2+(aq) + 2Cl^-(aq).