An example of a face centred cubic lattice is

Options

A. Zinc
B. Sodium
C. Copper
D. Caesium chloride

Explanation

To solve the question "An example of a face centred cubic lattice is," we will follow these steps:

### Step 1: Understand the Face Centred Cubic (FCC) Structure
The face-centred cubic (FCC) lattice is a type of crystal structure where atoms are located at each of the corners and the centers of all the faces of the cube. In an FCC lattice, there are a total of 4 atoms per unit cell.

### Step 2: Identify Characteristics of FCC
- **Atoms at corners**: 8 corners × 1/8 atom per corner = 1 atom
- **Atoms at faces**: 6 faces × 1/2 atom per face = 3 atoms
- **Total atoms in FCC unit cell**: 1 + 3 = 4 atoms

### Step 3: List Common Examples of FCC Lattices
Some common examples of materials that exhibit a face-centred cubic structure include:
- Copper (Cu)
- Silver (Ag)
- Gold (Au)
- Aluminum (Al)

### Step 4: Analyze the Given Options
From the question, we need to identify which of the provided options is an example of an FCC lattice. The video transcript mentions that:
- Zinc (Zn) is HCP (Hexagonal Close Packing)
- Sodium (Na) has a BCC (Body-Centered Cubic) structure
- Copper (Cu) is mentioned as having an FCC structure
- Cesium chloride (CsCl) has a BCC structure

### Step 5: Conclusion
Based on the analysis, the correct answer to the question is that **Copper (Cu)** is an example of a face-centred cubic lattice.

### Final Answer
**Copper (Cu)** is an example of a face-centred cubic lattice.

---