Question

Which of the following statement(s) is/are correct?

• A. Graphite is harder than diamond
• B. In diamond each C-atom is tetrahedrally surrounded by 4-equidistant neighbour
• C. Diamond shows less electrical conductivity as compare to graphite
• D. Diamond has the highest thermal conductivity of any known substance

Answer 1

Answer: (B), (C), (D)

Diamond has the highest thermal conductivity of any known substance

In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid 3-D structure.

Diamond is the hardest and has the highest thermal conductivity of any natural material. In diamond atoms are arranged in a crystal structure called diamond cubic.
$\Rightarrow$ Graphite is also an allotrope of carbon in which atoms are arranged in hexagonal arrangement.
Diamond does not conduct electricity although it is a good thermal conductor. Because it does not have any delocalized free electron in the outer shell of the carbon atom. But graphite is a good conductor of electricity because of delocalized $\pi -$bond electrons above and below the sheets of carbon atoms.