In fluorite structure, `100%` of `TVs` are occupied by cations.

Explanation

To solve the question regarding the occupancy of tetrahedral voids in the fluorite structure, we can break down the solution into a series of steps:

### Step-by-Step Solution:

1. **Understand the Fluorite Structure**: The fluorite structure is typically represented by the formula CaF2, where calcium (Ca²⁺) ions form a face-centered cubic (FCC) lattice, and fluoride (F⁻) ions occupy the tetrahedral voids.

2. **Identify the Occupancy of Tetrahedral Voids**: In the fluorite structure, each unit cell of the FCC lattice contains 8 tetrahedral voids. In the case of CaF2, it is the fluoride ions (F⁻) that occupy these tetrahedral voids.

3. **Analyze the Given Statement**: The question states that "100% of tetrahedral voids are occupied by cations." This implies that cations (like Ca²⁺) are filling the tetrahedral voids, which contradicts the established understanding of the fluorite structure.

4. **Determine the Correct Occupancy**: In the fluorite structure, it is actually the anions (F⁻) that occupy the tetrahedral voids, while the cations (Ca²⁺) occupy the FCC lattice sites. Therefore, the statement in the question is incorrect.

5. **Conclusion**: Based on the analysis, we conclude that the statement "100% of tetrahedral voids are occupied by cations" is incorrect. In the fluorite structure, tetrahedral voids are occupied by anions (F⁻), not cations.

### Final Answer:
The statement in the question is incorrect. In the fluorite structure, tetrahedral voids are occupied by anions (F⁻), while cations (Ca²⁺) occupy the FCC lattice.

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