Example of unit cell with crystallographic dimensions `anebnec,alpha=gamma=90^(@),betane90^(@)` is

Options

A. Calcite
B. Graphite
C. Rhombic sulphur
D. Monoclinic sulphur

Answer

To solve the question regarding the example of a unit cell with specific crystallographic dimensions, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Given Dimensions**:
- We have the dimensions: \( a = b = c \) (equal lengths).
- The angles are given as: \( \alpha = 90^\circ \), \( \gamma = 90^\circ \), and \( \beta \neq 90^\circ \).

2. **Identifying the Type of Unit Cell**:
- The conditions provided indicate that two angles are right angles (90 degrees), while one angle (beta) is not.
- This is characteristic of a **monoclinic unit cell**, where:
- Two axes are perpendicular to each other (alpha and gamma are 90 degrees).
- The third axis (c) is inclined, leading to beta being different from 90 degrees.

3. **Conclusion**:
- Based on the analysis of the dimensions and angles, the example of a unit cell that fits the criteria is a **monoclinic unit cell**.

### Final Answer:
The example of a unit cell with the given crystallographic dimensions is a **monoclinic unit cell**.

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