Edge length of `M^(+)X^(-)` (fcc structure) is `7.2^(@)A`. Assuming `M^(+)-X^(-)` contact along the cell edge, radius of `X(-)` ion is `(r_(M+)=1.6^(@)A)`:

Options

A. `2.0 Å`
B. `5.6 Å`
C. `2.8 Å`
D. `3.8 Å`

Explanation

To solve the problem, we need to find the radius of the `X^(-)` ion given the edge length of the face-centered cubic (FCC) structure and the radius of the `M^(+)` ion.

### Step-by-Step Solution:

1. **Identify the given values**:
- Edge length of the FCC structure, \( A = 7.2 \, \text{Å} \)
- Radius of the cation \( M^{+} \), \( r_{M^{+}} = 1.6 \, \text{Å} \)

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