which of the following feastures are not shown by quartz glass ?

Options

A. this is a crystalline solid
B. Refractive index is same in all the directions
C. this has define heat of fusion
D. this is also called super cooled liquid

Explanation

To determine which features are not shown by quartz glass, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Nature of Quartz Glass**:
- Quartz glass is known to be an amorphous solid, not a crystalline solid.
- **Conclusion**: The statement "this is a crystalline solid" is **not** true for quartz glass.

2. **Refractive Index**:
- Quartz glass exhibits isotropy, meaning its refractive index is the same in all directions.
- **Conclusion**: The statement "refractive index is same in all the directions" is **true** for quartz glass.

3. **Defined Heat of Fusion**:
- Quartz glass does not have a defined heat of fusion because it does not have a sharp melting point. Instead, it transitions from solid to liquid over a range of temperatures.
- **Conclusion**: The statement "this has defined heat of fusion" is **not** true for quartz glass.

4. **Super Cool Liquid**:
- Quartz glass is often referred to as a "supercooled liquid" due to its non-crystalline structure and the way it behaves when heated.
- **Conclusion**: The statement "this is also called super cool liquid" is **true** for quartz glass.

### Final Answer:
The features that are **not** shown by quartz glass are:
1. It is a crystalline solid.
2. It has defined heat of fusion.