6. Rumus kimia dari kation nikel berikut ini adalah A. Cu D. Ni^2+ B. Cu^2+ C. Ni^+ E. Ni^3+

The correct answer is **D. **. Here's why:* **Nickel (Ni)** is a transition metal, meaning it can form ions with different charges.* **Cations** are positively charged ions.* Nickel typically forms a +2 charge when it becomes an ion. Therefore, the correct chemical formula for the nickel cation is ** **.