If the radius of `Na^(+)` ion is `95 p m` and that of `Cl^(-)` ion is `181 p m`, then `:`

Options

A. (a) co-ordination no. Of `Na^(+)` is 6
B. (b) co-ordination no. Of `Cl^(-)` is 8
C. (c) co-ordination no. Of `Cl^(-)` is 4
D. (d) co-ordination no. Of `Na^(+)` is 8

Answer

To solve the problem, we need to determine the coordination numbers of the Na⁺ and Cl⁻ ions based on their ionic radii. Here’s a step-by-step solution:

### Step 1: Identify the given data
- Radius of Na⁺ ion = 95 pm (picometers)
- Radius of Cl⁻ ion = 181 pm (picometers)

### Step 2: Calculate the radius ratio
The radius ratio (r₁/r₂) is calculated using the formula:
\[ \text{Radius Ratio} = \frac{\text{Radius of Na}^+}{\text{Radius of Cl}^-} = \frac{95 \text{ pm}}{181 \text{ pm}} \]

### Step 3: Perform the calculation
Now, we perform the division:
\[ \text{Radius Ratio} = \frac{95}{181} \approx 0.524 \]

### Step 4: Determine the coordination number based on the radius ratio
We now analyze the radius ratio to determine the coordination number:
- If the radius ratio is between 0.414 and 0.732, the cation (Na⁺) occupies octahedral voids.
- Since our calculated radius ratio (0.524) falls within this range, Na⁺ occupies octahedral voids.

### Step 5: State the coordination number for Na⁺
The coordination number for octahedral voids is 6. Therefore, the coordination number of Na⁺ is:
\[ \text{Coordination Number of Na}^+ = 6 \]

### Step 6: Determine the coordination number for Cl⁻
In a close-packed structure (like CCP or HCP), the coordination number of the anion (Cl⁻) is also 6. Therefore, the coordination number of Cl⁻ is:
\[ \text{Coordination Number of Cl}^- = 6 \]

### Conclusion
Both Na⁺ and Cl⁻ ions have a coordination number of 6.

### Final Answer
The coordination numbers are:
- Coordination number of Na⁺ = 6
- Coordination number of Cl⁻ = 6