Question

Assertion (A) : Graphite is soft while diamond is very hard.
Reason (R) : Graphite has three dimensional structure while diamond has plánar.

• A. A and R both are correct and R is the correct explanation of A.
• B. A and R both are correct but R is not the correct explanation of A.
• C. A is correct but R is incorrect.
• D. A is incorrect while R is correct.

Answer 1

Answer: (C)

Graphite is soft while diamond is very hard In diamond, carbon is $s{p}^3$-hybridised. Each carbon thus forms covalent bonds with four other carbon atoms which lie at the corners of a reg:lar tetrahedron. As a result, diamond exists, as a three dimensional network solid. In graphite, carbon atom is $s{p}^2$-hybridised and is linked to three other carbon atoms by three single covalent bonds forming hexagonal layer. These hexagonal layers are held together by relatively weak van der Waals' forces, which makes it soft.