7. Rumus kimia dari anion nitrida ini adalah __ A. Ni D. N^2- B. Ni^2+ E. N^3- C. Ni^3+

The correct answer is **E. **. Here's why:* **Nitride** is a negatively charged ion formed from the nitrogen atom.* Nitrogen has 5 valence electrons. To achieve a stable octet, it needs to gain 3 electrons.* This gain of 3 electrons results in a -3 charge, forming the nitride ion ( ).Let's look at why the other options are incorrect:* **A. Ni:** This represents the element nickel, not the nitride ion.* **B. :** This represents the nickel(II) cation, not the nitride ion.* **C. :** This represents the nickel(III) cation, not the nitride ion.* **D. :** This represents a nitrogen ion with a -2 charge, which is not the stable form of the nitride ion.