In which of the following structures, the coordination number of both the ions are same ?

Options

A. Cesium chloride
B. Sodium chloride
C. Zinc sulphide
D. Sodium oxide

Explanation

To determine which structures have the same coordination number for both ions, we will analyze the coordination numbers of the ions in the given ionic crystals: Cesium Chloride (CsCl), Sodium Chloride (NaCl), Zinc Sulphide (ZnS), and Sodium Oxide (Na2O).

### Step-by-Step Solution:

1. **Cesium Chloride (CsCl)**:
- In CsCl, the Cs⁺ ions are located in the cubic voids of the FCC packing of Cl⁻ ions.
- The coordination number of Cs⁺ is 8 (since it is surrounded by 8 Cl⁻ ions).
- The coordination number of Cl⁻ is also 8 (since it is surrounded by 8 Cs⁺ ions).
- **Conclusion**: The coordination numbers are the same (8:8).

2. **Sodium Chloride (NaCl)**:
- In NaCl, Na⁺ ions occupy the octahedral voids in the FCC packing of Cl⁻ ions.
- The coordination number of Na⁺ is 6 (since it is surrounded by 6 Cl⁻ ions).
- The coordination number of Cl⁻ is also 6 (since it is surrounded by 6 Na⁺ ions).
- **Conclusion**: The coordination numbers are the same (6:6).

3. **Zinc Sulphide (ZnS)**:
- In ZnS, Zn²⁺ ions occupy half of the tetrahedral voids in the FCC packing of S²⁻ ions.
- The coordination number of Zn²⁺ is 4 (since it is surrounded by 4 S²⁻ ions).
- The coordination number of S²⁻ is also 4 (since it is surrounded by 4 Zn²⁺ ions).
- **Conclusion**: The coordination numbers are the same (4:4).

4. **Sodium Oxide (Na2O)**:
- In Na2O, O²⁻ ions are in FCC packing, and Na⁺ ions occupy tetrahedral voids.
- The coordination number of O²⁻ is 8 (since it is surrounded by 8 Na⁺ ions).
- The coordination number of Na⁺ is 4 (since each Na⁺ is surrounded by 4 O²⁻ ions).
- **Conclusion**: The coordination numbers are not the same (8:4).

### Final Answer:
The structures in which the coordination number of both ions is the same are:
- Cesium Chloride (CsCl)
- Sodium Chloride (NaCl)
- Zinc Sulphide (ZnS)