Question

Which of the following substances are crystalline allotrope of carbon? (i) Diamond (ii) Charcoal (iii) Graphite (iv) Lamp black (v) Coke (vi) Fullerene
A.(i) to (vi) all
B.(i) (ii) & (iv)
C.(i), (iii) & (vi)
D.(iv), c), (v)

Answer 1

There are eight allotropes of carbon which are: Diamond, Graphite, 60 Buckminsterfullerene, C540 Fullerite, Lonsdaleite, C70 Fullerene, Amorphous carbon, Crystalline allotropes are diamond, graphite, Fullerite, Single-walled carbon nanotube, C60, carbon-nanotube

Complete step by step answer:
The presence of one element in various structures which have distinctive physical properties, but comparable chemical properties are known as Allotropy. Different types of an element are called Allotropes or Allotropic Structures. Carbon demonstrates allotropy due to its valency. The different allotropic types of carbon can be characterized into two classes mainly, which are Crystalline form and Amorphous form. In nature, carbon occurs in free as well as in combined states. The free forms of Carbon are diamond, graphite and coal. In a combined state, carbon occurs in the form of its compounds in solid, liquid and gaseous states. Various physical forms of an element having Different physical properties, but similar Chemical properties are known as allotropes. Carbon has mainly two allotropic forms, Crystalline and amorphous forms. Crystalline in Forms of an element have definite geometric Shapes when broken. Diamond, graphite and Fullerene are crystalline forms of carbon.
a)Diamonds is an Allotrope of Carbon. Artificial or Synthetic diamonds are made from graphite by exposing it to a very high temperature and pressure in absence of air.
b)Graphite is another Allotrope of Carbon, prepared artificially by heating powdered coke mixed with a little sand and ferric oxide in an electric furnace to a temperature of about $3000^\circ C$ .
c)Fullerene or Buckminsterfullerene is another known Allotrope of Carbon. It is found in interstellar dust, soot, carbon rich rocks and in the geological formations of earth.

Therefore, the correct answer is option (C).

Note: Few hypothetical carbon allotropes denser than diamond are known. These allotropes can be divided in two groups: the first are hypothetically stable at ambient conditions; the second are high-pressure carbon allotropes which become quasi-stable only at high pressure.