The structue of sodium chloride crystal is `:`

Options

A. Body centred cubic lattice
B. Face centred cubic lattice
C. Octahedral
D. Square planar

Answer

### Step-by-Step Solution

1. **Understanding the Structure of Sodium Chloride (NaCl)**:
Sodium chloride (NaCl) crystallizes in a face-centered cubic (FCC) lattice structure. In this arrangement, the sodium ions (Na⁺) and chloride ions (Cl⁻) are arranged in a specific manner.

**Hint**: Recall that NaCl is commonly known as table salt and has a well-defined crystal structure.

2. **Coordination Number**:
In the NaCl structure, each sodium ion is surrounded by six chloride ions, and each chloride ion is surrounded by six sodium ions. This gives both ions a coordination number of 6.

**Hint**: Coordination number refers to the number of nearest neighboring ions surrounding a particular ion in the crystal lattice.

3. **Lattice Type**:
The arrangement of ions in NaCl can be described as a face-centered cubic (FCC) lattice. In this type of lattice, the ions occupy the corners and the centers of the faces of the cube.

**Hint**: Visualize the cubic structure and remember that in FCC, atoms are located at the corners and the centers of each face of the cube.

4. **Octahedral Voids**:
In the FCC lattice of NaCl, the sodium ions occupy the octahedral voids formed by the chloride ions. Each octahedral void is surrounded by six ions.

**Hint**: An octahedral void is a type of interstitial site in the crystal lattice where an ion can fit in between the surrounding ions.

5. **Radius Ratio**:
The radius ratio of the cation (Na⁺) to the anion (Cl⁻) in NaCl is typically between 0.225 and 0.414. This ratio is important for determining the stability of the ionic compound.

**Hint**: The radius ratio helps predict the type of structure that will form based on the relative sizes of the ions.

6. **Comparison with Other Structures**:
Many other compounds exhibit a similar structure to NaCl, including various alkyl halides and metal oxides. This similarity arises from the comparable ionic sizes and coordination numbers.

**Hint**: Consider how different ionic compounds can share similar crystal structures based on their ionic characteristics.

### Conclusion
The structure of sodium chloride (NaCl) is a face-centered cubic lattice with a coordination number of 6 for both sodium and chloride ions. The ions are arranged such that each Na⁺ is surrounded by six Cl⁻ and vice versa, forming a stable ionic compound.