Question

Which is an example of amorphous carbon?
A.Charcoal
B.Coke
C.Lamp black
D.All of the above

Answer 1

Hint: Basically, amorphous carbon is free, reactive carbon that does not have any crystalline structure. True amorphous carbon has localized pi-electrons and its bonds which are formed are inconsistent with other allotropes of carbon.

Complete step by step answer:
Generally, the phenomenon by which an element can exist in more than one physical state is called allotropy. There are two allotropes of carbon namely amorphous carbon allotropes and crystalline carbon allotropes. The allotropes of carbon can be either amorphous or crystalline.

Now, in mineralogy, amorphous carbon is generally used for coal, soot, carbide-derived carbon and other impure forms of carbon that are neither graphite or diamond. Moreover, chemical bonds among atoms are a mixture of $s{p^2}$ and $s{p^3}$ hybridized bonds with a high concentration of bonds. Because the amorphous carbon is thermodynamically in a metastable state and the ratio of these bonds is variable, so the properties of amorphous carbon greatly depend on the formation methods and conditions. In the laboratory, amorphous carbon can be produced by physical vapor deposition, chemical vapor deposition and ion irradiation of diamond or graphite.
Now, all the options are correct as charcoal and coal are forms of amorphous carbon and lamp black is a type of carbon obtained from the soot of burned fat, oil, tar and resin.

Hence, option D is correct.

Note: Diamond is a well-known allotrope of carbon that exhibits hardness and high dispersion of light. The other one is graphene. It is a single layer of carbon atoms arranged in one plane. It is further a material of interest due to its high electron mobility and its application in electronics.