The unit cell present in ABCABC closed packing of atoms is

Options

A. Hexagonal
B. Tetragonal
C. Face centred cube
D. Simple cube

Answer

To determine the unit cell present in ABCABC closed packing of atoms, we can follow these steps:

### Step 1: Understand the Packing Types
- The ABCABC closed packing refers to a specific arrangement of atoms in a three-dimensional space where layers of atoms are stacked in a repeating pattern.
- There are two main types of close packing: Hexagonal Close Packing (HCP) and Cubic Close Packing (CCP).

### Step 2: Identify the Types of Close Packing
- **HCP (Hexagonal Close Packing)**: In HCP, the arrangement of atoms forms a hexagonal structure. The coordination number is 12, meaning each atom is in contact with 12 others.
- **CCP (Cubic Close Packing)**: In CCP, the arrangement of atoms forms a cubic structure. The coordination number is also 12.

### Step 3: Relate ABCABC to Close Packing
- The ABCABC sequence indicates that the layers are stacked in a way that each layer is offset from the one below it, which is characteristic of HCP.
- In contrast, if it were an ABAB type stacking, it would indicate CCP.

### Step 4: Conclusion
- Since the question specifies "ABCABC" stacking, we conclude that the unit cell present is of the Hexagonal Close Packing (HCP) type.

### Final Answer
The unit cell present in ABCABC closed packing of atoms is **Hexagonal Close Packing (HCP)**.

---