Question

Which option correctly defines the state of glass?

• A. Crystalline solid
• B. Super cooled liquid
• C. Condensed gas
• D. Liquid crystal

Hint:

Glass has no sharp melting point and no regular lattice, think amorphous.

Answer 1

The Correct Option is B

Step 1: Recall the difference between crystalline and amorphous solids. Crystalline solids have long range order, a sharp melting point, and a definite geometric shape, like NaCl or quartz. Amorphous solids, such as glass, have only short range order and soften gradually over a range of temperature instead of melting sharply.
Step 2: Glass is manufactured by melting silica (SiO₂) with fluxes like soda ash and lime, then cooling the melt rapidly so the atoms do not get time to arrange into a regular crystal lattice. The random, disordered arrangement typical of the liquid state gets essentially frozen in place. Because of this, glass is described as a super cooled liquid, it has the internal disorder of a liquid but the mechanical rigidity of a solid at room temperature.
Step 3: Now eliminate the rest. Crystalline solid is wrong because glass has no long range periodic order and no sharp melting point, unlike true crystalline solids. Condensed gas is not a meaningful description here, gases condense into liquids, not into rigid glass structures. Liquid crystal is a different, specific phase where rod shaped or disc shaped molecules retain partial orientational order, ordinary glass shows no such directional molecular ordering.
Step 4: Hence super cooled liquid, option B, correctly describes glass.