An ammoniacal metal salt solution gives a brilliant red precipitate on addition of dimethylglyoxime. The metal ion is:

Options

A. `Co^(2+)`
B. `Fe^(2+)`
C. `Ni^(2+)`
D. `Cu^(2+)`

Answer

To solve the question, we need to identify the metal ion that forms a brilliant red precipitate when dimethylglyoxime is added to an ammoniacal metal salt solution. Here’s a step-by-step solution:

### Step 1: Understand the Role of Dimethylglyoxime
Dimethylglyoxime (DMG) is a bidentate ligand, meaning it has two donor atoms that can coordinate with a metal ion. It is commonly used to test for the presence of certain metal ions.

**Hint:** Remember that bidentate ligands can form chelate complexes with metal ions.

### Step 2: Identify the Precipitate
When dimethylglyoxime is added to a solution containing metal ions, it can form a complex that precipitates out of the solution. The question specifies that a brilliant red precipitate is formed.

**Hint:** Pay attention to the color of the precipitate, as it can help identify the metal ion.

### Step 3: Recognize the Metal Ion Associated with the Precipitate
The brilliant red precipitate formed with dimethylglyoxime is specifically associated with nickel ions (Ni²⁺). The complex formed is known as Ni(DMG)₂, which is responsible for the red color.

**Hint:** Recall that specific metal ions have characteristic colors when they form complexes with ligands.

### Step 4: Conclusion
Based on the information above, the metal ion present in the ammoniacal metal salt solution that gives a brilliant red precipitate upon the addition of dimethylglyoxime is nickel (Ni²⁺).

**Final Answer:** The metal ion is Nickel (Ni²⁺).