When molten zinc is cooled to solid state, it assumes `hcp` structure. Then the number of nearest neighbours of zine atom will be

Options

A. 4
B. 6
C. 8
D. 12

Explanation

To determine the number of nearest neighbors of a zinc atom in its hcp (hexagonal close-packed) structure, we can follow these steps:

### Step 1: Understand the Structure
Zinc crystallizes in a hexagonal close-packed (hcp) structure. In this structure, each zinc atom is surrounded by other zinc atoms.

**Hint:** Recall the arrangement of atoms in hcp structure, which consists of two layers of atoms.

### Step 2: Identify Coordination Number
The coordination number is defined as the number of nearest neighbor atoms surrounding a central atom.

**Hint:** In hcp, each atom is surrounded by atoms in the same layer and in adjacent layers.

### Step 3: Count Nearest Neighbors
In the hcp structure:
- Each atom has 6 nearest neighbors in the same layer.
- There are 3 nearest neighbors from the layer above.
- There are 3 nearest neighbors from the layer below.

Thus, the total number of nearest neighbors for a zinc atom in hcp is:
- Neighbors in the same layer: 6
- Neighbors in the layer above: 3
- Neighbors in the layer below: 3

Total nearest neighbors = 6 (same layer) + 3 (above) + 3 (below) = 12.

**Hint:** Visualize the arrangement of atoms to help count the neighbors accurately.

### Step 4: Conclusion
The coordination number of zinc in the hcp structure is 12.

**Final Answer:** The number of nearest neighbors of a zinc atom is 12.