Dimethylglyoxime is used from the gravimetic estimation of ______ion .

Answer

**Step-by-Step Solution:**

1. **Understanding Dimethylglyoxime (DMG):**
- Dimethylglyoxime, often abbreviated as DMG, is a bidentate ligand that can form complexes with certain metal ions.

2. **Identifying the Ion for Gravimetric Estimation:**
- The question asks for the specific ion that can be estimated gravimetrically using DMG.
- DMG is known to form stable complexes with nickel ions.

3. **Reaction of DMG with Nickel Ion:**
- When DMG reacts with nickel(II) ions (Ni²⁺), it forms a complex that precipitates out of solution.
- The reaction can be represented as:
\[ \text{Ni}^{2+} + 2 \text{DMG} \rightarrow \text{Ni(DMG)}_2 \text{ (precipitate)} \]
- This complex is characterized by a distinct cherry-red color.

4. **Conclusion:**
- Based on the above information, we conclude that dimethylglyoxime is used for the gravimetric estimation of nickel ions (Ni²⁺).

**Final Answer:**
Dimethylglyoxime is used for the gravimetric estimation of **Ni²⁺ ion**.

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