Which of the following is an amorphous solid?
(A) Graphite (C)
(B) Quartz glass $\left( {Si{O_2}} \right)$
(C) Chrome alum
(D) Silicon carbide $\left( {SiC} \right)$

Hint:Hint: Glass is mostly considered as an amorphous solid. An amorphous solid can be considered as having a random set-up of atoms, as found in a gas, but it may be more reasonable to assume that it has no long-range order as in crystalline solids.

Complete step by step solution:
>An amorphous or non-crystalline solid is defined as a solid that lacks the long-range order that is a widely considered characteristic of a crystal. To be more precise, an amorphous solid can be said as any non-crystalline solid in which the said atoms and molecules will not be organized in a definite lattice pattern. Such solids, for example, will include glass, plastic, and gel.
> The only two natural carbon polymers are graphite and diamonds. Graphite is basically a two-dimensional, flat crystal structure, with diamonds being three-dimensional. Graphite is a crystalline (not amorphous) covalent crystal.
> Silicon carbide is a wide-band gap semiconductor in the crystalline phase as well as the amorphous, with a wide range of atomic configurations. Depending on the preparation conditions, the structure and properties of silicon carbide.
Note that Quartz is considered as a crystalline solid while quartz glass is considered as an amorphous solid.

Therefore option (B) Glass is the correct option.

Note: Silica glass is not the only amorphous solid that fits the profile for optical functions. The poly(methyl methacrylate), acrylic glass is a polymer which corresponds to the amorphous solid definition of the glass. Quartz is considered as an amorphous solid due to the absence of long-range order of arrangement of constituting particles.