A co-ordination complex has the formula `PtCl_(4).2KCl`. Electrical conductance measurements indicate the presence of three ion in one formula unit. Treatment with `AgNO_(3)` produces no precipitate of `AgCl`. What is the co-ordination number of Pt in this complex ?

Options

A. 5
B. 6
C. 4
D. 3

Explanation

To determine the coordination number of platinum in the coordination complex `PtCl_(4).2KCl`, we can follow these steps:

### Step 1: Analyze the Formula
The given formula of the coordination complex is `PtCl_(4).2KCl`. This indicates that there are 4 chloride ions (Cl⁻) associated with the platinum (Pt) ion and 2 potassium ions (K⁺) outside the coordination sphere.

**Hint:** Look at the components of the coordination complex to identify the ions involved.

### Step 2: Understand Electrical Conductance
The problem states that electrical conductance measurements indicate the presence of three ions in one formula unit of the complex. This means when the complex is dissolved in solution, it dissociates into three ions.

**Hint:** Consider how many ions are produced when the complex dissociates.

### Step 3: Determine the Dissociation
When the complex `PtCl_(4).2KCl` dissociates in solution, it can be represented as:
\[ PtCl_4 + 2KCl \rightarrow PtCl_6^{2-} + 2K^+ \]

Here, the dissociation produces:
- 1 ion of `PtCl_6^{2-}` (the coordination complex)
- 2 ions of `K^+`

Thus, the total number of ions produced is:
\[ 1 (PtCl_6^{2-}) + 2 (K^+) = 3 \text{ ions} \]

**Hint:** Write down the dissociation equation to visualize the ions produced.

### Step 4: Analyze Treatment with AgNO₃
The problem states that treatment with `AgNO₃` produces no precipitate of `AgCl`. This indicates that all the chloride ions are coordinated to the platinum ion and are not free to react with silver nitrate.

**Hint:** Consider what it means for ions to be "inside" or "outside" the coordination sphere.

### Step 5: Identify Coordination Number
The coordination number is defined as the number of ligand atoms that are directly bonded to the central metal atom. In this case, since there are 6 chloride ions coordinated to platinum in the complex `PtCl_6^{2-}`, the coordination number of platinum is 6.

**Hint:** Count the number of ligands directly bonded to the central metal ion.

### Conclusion
The coordination number of platinum in the complex `PtCl_(4).2KCl` is 6.

**Final Answer:** The coordination number of Pt in this complex is 6.

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