Monoclinic sulphur is an example of monoclinic cystal system. What are the characteristics of the crystal system ?

Options

A. `a ne b ne c , alpha = beta = gamma = 90^@`
B. `a ne b ne c , alpha ne beta ne gamma ne 90^@`
C. `a = b ne c , alpha = beta = gamma = 90^@`
D. `a ne b ne c , alpha = gamma = 90^@, beta ne 90^@`

Answer

To answer the question about the characteristics of the monoclinic crystal system, we can break down the solution into clear steps:

### Step-by-Step Solution:

1. **Identify the Crystal System**:
- The monoclinic crystal system is one of the seven crystal systems in crystallography.

2. **Understand the Axes**:
- In the monoclinic system, there are three axes:
- \( a \) and \( b \) are of equal length, i.e., \( a = b \).
- \( c \) is of a different length, i.e., \( c \neq a \) and \( c \neq b \).

3. **Analyze the Angles**:
- The angles between the axes are defined as follows:
- The angle \( \alpha \) (between axes \( b \) and \( c \)) is equal to \( 90^\circ \).
- The angle \( \beta \) (between axes \( a \) and \( b \)) is not equal to \( 90^\circ \).
- The angle \( \gamma \) (between axes \( a \) and \( c \)) is equal to \( 90^\circ \).

4. **Summarize the Characteristics**:
- In summary, the characteristics of the monoclinic crystal system are:
- Two axes are of equal length (\( a = b \)).
- The third axis is of a different length (\( c \)).
- Two angles are \( 90^\circ \) (i.e., \( \alpha \) and \( \gamma \)), while one angle (\( \beta \)) is not \( 90^\circ \).

5. **Conclusion**:
- Monoclinic sulfur exemplifies this crystal system, demonstrating these specific geometric properties.