Incorrect statements regarding quartz glass are-

(a) This is a crystalline solid

(b) Refractive index is same in all the directions

(c) This has definite heat of fusion

(d) This is also called supercooled liquid

1. (a, b)

2. (b, c)

3. (c, d)

4. (a, c)

Hint: Quartz glass is an amorphous solid so it has not definite heat of fusion
Quartz glass is an amorphous solid so it has not definite heat of fusion. This is due to short-range order of molecules while quartz
glass is also known as a supercooled liquid. Due to isotropic in nature, it has the same refractive index in all directions.