`S_(1)`: Distance between `Na^(+) " & " Cl^(-)` in NaCl crystal is more than half of edge length.
`S_(2)`: The no. of triangular viods in the given arrangement in the enclosed region is 3

`S_(3)`: In ZnS structure, `2Zn^(2+) " & " 2S^(2-)` ions are present in each unit cell

Options

A. FFT
B. FTF
C. TFF
D. FFF

Explanation

To analyze the statements provided in the question, we will evaluate each statement step by step.

### Step 1: Evaluate Statement S1
**Statement S1**: "Distance between Na⁺ and Cl⁻ in NaCl crystal is more than half of edge length."

1. **Understanding the NaCl Structure**: In a NaCl crystal, the Na⁺ and Cl⁻ ions are arranged in a face-centered cubic (FCC) lattice. The edge length of the unit cell (a) is related to the ionic radii of Na⁺ and Cl⁻.
2. **Distance Calculation**: The distance between Na⁺ and Cl⁻ ions in the NaCl crystal is equal to the sum of their ionic radii (r_Na + r_Cl).
3. **Comparison with Edge Length**: The edge length (a) of the NaCl unit cell is equal to 2(r_Na + r_Cl). Therefore, the distance between Na⁺ and Cl⁻ is actually less than half of the edge length (a/2).
4. **Conclusion**: Thus, this statement is **false**.

### Step 2: Evaluate Statement S2
**Statement S2**: "The number of triangular voids in the given arrangement in the enclosed region is 3."

1. **Understanding Triangular Voids**: In a close-packed arrangement of spheres (like in FCC), triangular voids can be formed between the spheres.
2. **Counting Triangular Voids**: In a typical close-packed structure, there are 4 triangular voids formed in the arrangement.
3. **Conclusion**: Therefore, this statement is also **false**.

### Step 3: Evaluate Statement S3
**Statement S3**: "In ZnS structure, 2Zn²⁺ and 2S²⁻ ions are present in each unit cell."

1. **Understanding the ZnS Structure**: The zinc blende structure (ZnS) consists of a face-centered cubic lattice of Zn²⁺ ions with S²⁻ ions occupying half of the tetrahedral voids.
2. **Counting Ions in the Unit Cell**: In the ZnS structure, there are actually 4 Zn²⁺ ions and 4 S²⁻ ions per unit cell.
3. **Conclusion**: Thus, this statement is also **false**.

### Final Conclusion
All three statements (S1, S2, and S3) are false.