Question

Glass is a:
A. Crystalline solid
B. Solid having a definite melting point
C. Supercooled liquid
D. Chemical compound

Answer 1

Hint: Glass is a non-metallic and inorganic material. Glass is a type of amorphous solid, and a mixture of silica, lime and soda ash out of which silica is the main constituent.

Complete answer:
Glass is a non-crystalline amorphous and transparent solid. Amorphous solids are the solids that have a lack of long-range ordered arrangement of particles.
The glass is not crystalline solid so option (A) is incorrect.
Amorphous solids have a range of temperature of melting point. The bonds in amorphous solids do not break in this range. Amorphous solids melt and become softer in this range.
The glass is non-crystalline solid so does not have a definite melting point, so option (B) is incorrect.
When liquid does not solidify below their melting point, the state is known as supercooled liquid. Amorphous solid forms supercooled liquid. The supercooled liquid freezes into solids at the temperature known as glass transition temperature. The glass is a super cooled liquid, so option (C) is correct.
The chemical composition of glass is sand (silica or silicon dioxide), calcium carbonate (lime), magnesium carbonate (dolomite) and soda ash (sodium carbonate). Glass also has alkali and alkaline earth metals. So, glass is a mixture of chemicals. It is not a chemical compound. So, option (D) is incorrect.

Hence the correct option is (C).

Note: The non-crystalline solids have shout range or arrangement of particles and do not have a sharp melting point and thus form supercooled liquid. The crystalline solids have a long-range ordered arrangement of particles and melt at a definite melting point.