Which of the following fcc structure contain cations in alternate tetrahedral voids?

Options

A. NaCl
B. ZnS
C. `Na_(2)O`
D. `CaF_(2)`

Explanation

To determine which of the following FCC structures contains cations in alternate tetrahedral voids, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding FCC Structure**:
- FCC (Face-Centered Cubic) structure has atoms located at each of the corners and the centers of all the faces of the cube. Each FCC unit cell has 8 tetrahedral voids.

2. **Analyzing NaCl**:
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