In iodide of Million's base formed by the reaction of Nessler's reagent with `NH_(3)`, the coordination number of Hg will be

Options

A. 2
B. 3
C. 4
D. 6

Answer

To determine the coordination number of mercury (Hg) in the iodide of Million's base formed by the reaction of Nessler's reagent with ammonia (NH₃), we can follow these steps:

### Step 1: Understand the Reaction
Nessler's reagent, which contains mercury, reacts with ammonia to form a complex. The reaction can be represented as:
\[ \text{NH}_4^+ + \text{HgI}_4^{2-} \rightarrow \text{[Hg(NH}_2)_2]^{+} + 7 \text{I}^- + 3 \text{H}_2\text{O} \]

### Step 2: Identify the Complex Formation
In the reaction, mercury (Hg) forms a complex with ammonia. The complex can be represented as:
\[ \text{Hg}^{2+} + 2 \text{NH}_3 \rightarrow \text{[Hg(NH}_2)_2]^{+} \]

### Step 3: Determine the Coordination Number
The coordination number is defined as the number of ligand atoms that are bonded to the central metal atom. In this case, Hg is coordinated by two ammonia (NH₃) molecules. Therefore, the coordination number of Hg in this complex is 2.

### Step 4: Conclusion
Thus, the coordination number of mercury in the iodide of Million's base formed by the reaction of Nessler's reagent with ammonia is **2**.

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