Question

The correct statement(s) related to allotropes of carbon is/are:

• A. graphite is the most stable allotropes of carbon and having a two dimensional sheet like structure of hexagonal rings of carbon
• B. diamond is the hardest allotrope of carbon and having a three dimensional network structure of C$\left(s{p}^3\right)$
• C. fullerene($C_{60}$) is recently discovered non-crystalline allotrope of carbon having a football-like structure
• D. vander waal's force of attraction acts between the layers of graphite 6.14 A away from each other

Answer 1

Answer: (A), (B)

The correct options are
A graphite is the most stable allotropes of carbon and having a two dimensional sheet like structure of hexagonal rings of carbon
B diamond is the hardest allotrope of carbon and having a three dimensional network structure of C$\left(s{p}^3\right)$

Structure of graphite and diamond are shown in figure.
A) Graphite has delocalized pi-electrons over the entire sheet. This delocalization lowers the energy of the system, leading to greater thermodynamic stability.
B) In diamond each carbon atom undergoes $s{p}^3$ hybridisation and linked to four other carbon atoms by using hybridised orbitals in tetrahedral manner. It is very difficult to break extended covalent bonding and therefore, diamond is a hardest substance on the earth. It is used as an abrasive for sharpening hard tools in making dies (die casting) and in the manufacture of tungsten filament for electric light bulbs.
C) Fullerenes are the only pure form of carbon because they have smooth structure without having dangling bonds. Fullerene are cage like molecules. $C_{6}0$ molecule has a shape like soccer ball and called Buckminster fullerene and it was discovered in 1970.
D) Graphite has layered structure. Layers are held by van der Waals forces and distance between two layers is 3.4 $A^o$.