The crystal lattice of NaCl is

Options

A. Face-centred cubic lattice
B. Body-centred cubic lattice
C. Simple cubic lattice
D. Hexagonal close packing

Answer

**Step-by-Step Solution:**

1. **Understanding the Crystal Structure**: Sodium chloride (NaCl) crystallizes in a specific arrangement known as a crystal lattice. The type of lattice it forms is crucial for understanding its properties.

2. **Identifying the Lattice Type**: NaCl adopts a face-centered cubic (FCC) lattice structure. In this arrangement, the ions are arranged in a way that maximizes packing efficiency.

3. **Ionic Arrangement**: In the NaCl lattice, the sodium ions (Na⁺) and chloride ions (Cl⁻) are arranged alternately. The chloride ions (Cl⁻) occupy the face-centered positions of the cubic unit cell, while the sodium ions (Na⁺) occupy the octahedral voids created by the chloride ions.

4. **Coordination Number**: The coordination number for NaCl is 6, meaning each sodium ion is surrounded by six chloride ions and vice versa. This is a characteristic feature of the FCC lattice.

5. **Lattice Points Calculation**: In a face-centered cubic lattice, there are 4 formula units of NaCl per unit cell. This is calculated as follows:
- Each corner of the cube contributes 1/8 of an ion (8 corners).
- Each face center contributes 1/2 of an ion (6 faces).
- Thus, the total contribution is (8 corners * 1/8) + (6 faces * 1/2) = 1 + 3 = 4.

6. **Conclusion**: Therefore, the crystal lattice of NaCl is a face-centered cubic (FCC) lattice with a coordination number of 6 and a Z value of 4.

**Final Answer**: The crystal lattice of NaCl is a face-centered cubic (FCC) lattice.

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