Question

Which of the following is/are amorphous solid(s)?

• A. $SiC$
• B. $Ca{F}_2$
• C. Glass
• D. Plastic

Answer 1

Answer: (C), (D)

Plastic

Amorphous solids does not have a definite geometrical shape.
Characteristic of amorphous solids:
1. They don’t have long-range repetitive internal structures that are found in crystals.
2. Regular patterns are scattered and in between the arrangement is disordered.
3. They are formed by sudden cooling of a liquid, so they can be called supercooled liquids or pseudo solid
4. These are isotropic, which can show same properties in all directions.
5. They don't have sharp melting point due to the disordered arrangements. They have a range of temperature for melting.
6. They can be cut along random directions and have irregular surfaces.

Glass and plastics have these characteristics and they are the popular examples of amorphous solids.

$SiC$ is a covlaent solid and $Ca{F}_2$ is an ionic solid. They comes under crystalline solids since they have a 3D arrangement of cation and anions in a ordered way and have a well defined regular shapes.