In a crystal `anebnec,alpha=gamma=90^(@)" and "betane90^(@)`.It is

Options

A. Monoclinic
B. Rhombic
C. Trigonal
D. Tetragonal

Explanation

To determine the type of crystal system given the conditions of the crystal, we can follow these steps:

### Step 1: Identify the parameters
We are given:
- Edge lengths: \( a \neq b \neq c \)
- Angles: \( \alpha = \gamma = 90^\circ \) and \( \beta \neq 90^\circ \)

### Step 2: Analyze the conditions
In crystallography, the parameters of a crystal system are defined by the lengths of the edges and the angles between them. The conditions provided indicate:
- The three edge lengths are not equal, which suggests that the crystal does not belong to a cubic system.
- The angles \( \alpha \) and \( \gamma \) being \( 90^\circ \) indicates that the crystal has rectangular faces in two dimensions.
- The angle \( \beta \) being not equal to \( 90^\circ \) indicates that the third dimension is not rectangular.

### Step 3: Determine the crystal system
Based on the provided conditions:
- The unequal edge lengths and the specific angles suggest that this crystal system is not orthorhombic (where all angles are \( 90^\circ \)).
- The only crystal system that fits the criteria of having two angles at \( 90^\circ \) and one angle that is not \( 90^\circ \) is the monoclinic system.

### Conclusion
Thus, the type of crystal system described is **monoclinic**.

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