The unit cell present in ABCABC, closet packing of atoms is:

Options

A. Hexagonal
B. tetragonal
C. Face centred cubic
D. primitive cubic

Answer

To determine the unit cell present in the ABCABC closest packing of atoms, we will analyze the given options step by step.

### Step 1: Understanding Closest Packing
In closest packing, atoms are arranged in a way that maximizes the number of nearest neighbors. The two common types of closest packing are:
- Hexagonal Close Packing (HCP)
- Face-Centered Cubic (FCC)

### Step 2: Analyzing the Stacking Sequence
The question specifies the stacking sequence as ABCABC. This means that the arrangement of layers alternates in a specific manner:
- The first layer is A
- The second layer is B
- The third layer is C
- The fourth layer returns to A, and so on.

### Step 3: Evaluating the Options
1. **Hexagonal Close Packing (HCP)**:
- The stacking sequence is ABAB.
- **Conclusion**: This does not match ABCABC.

2. **Tetragonal**:
- The stacking sequence can be AA (primitive) or ABAB (body-centered).
- **Conclusion**: This does not match ABCABC.

3. **Face-Centered Cubic (FCC)**:
- The stacking sequence is indeed ABCABC.
- **Conclusion**: This matches the required stacking sequence.

4. **Primitive Cubic**:
- The stacking sequence is AA.
- **Conclusion**: This does not match ABCABC.

### Step 4: Final Conclusion
Based on the analysis, the unit cell present in the ABCABC closest packing of atoms is the **Face-Centered Cubic (FCC)**.

### Final Answer
The unit cell present in ABCABC closest packing of atoms is **Face-Centered Cubic (FCC)**.

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