Question

Consider the following statements.
I. In diamond each carbon atom is linked tetrahedrally to four other carbon atoms by $s{p^3}$bond.
II. Graphite has planar hexagonal layers of carbon atoms held by weak Vander Waals forces.
III. Silicon exists in the diamond structure because of its tendency to form $p\pi - p\pi$ bond to itself.
(A) only I and II are correct.
(B) only I is correct
(C) only II and III are correct.
(D) all the above statements are correct

Answer 1

In order to answer this question, we must be aware of the structure of Diamond, Graphite and the Silicon. Graphite and diamond are known to be the allotropes of Carbon and Silicon will come under the carbon family.

Complete Solution :
- Let us now deeply understand about the structure of all three- diamond, graphite and Silicon. First let us see about diamonds. Diamond is present in the solid form in which the carbon atoms are arranged in a crystal structure. Because of this reason, diamonds will be having a rigid structure. Each carbon atom present in Diamond is bonded to four other carbon atoms tetrahedrally and therefore, it will be having a $s{p^3}$ hybridisation.
- Now let us see about Graphite. Graphite is having a layered structure. Each carbon atom present in the graphite is attached to three other carbon atoms. Graphite will be having a $s{p^2}$ hybridisation. It will be having a 2D sheet like structure and these layers of sheets are held together by weak Vander Waals force.
- Silicon is a hard, brittle crystalline structure. It will be having different structures based on the bonding of its atoms.
So, the correct answer is “Option B”.

Note: We have to note that though both graphite and diamonds are allotropes of carbon, they are not the same. Let us see some of the differences between Diamond and graphite.

DIAMOND	GRAPHITE
It has a crystalline structure.	It has a layered structure.
It will be having $s{p^3}$ hybridisation.	It will be having $s{p^2}$ hybridisation.
Tetrahedral geometry.	Planar geometry.
Poor conductor.	Good conductor.