Question

Diamond is a bad conductor of electricity but a good conductor of heat.
$
  (a){\text{ True}} \\
  {\text{(b) False}} \\
$

Answer 1

Hint – In this question think of the concept that flow of electricity is dependent upon the free electrons present in a compound and in diamond the outermost electrons form covalent bonds which makes non-availability of free electrons within diamond.

Complete answer:
As we know diamond is a giant covalent structure i.e. each carbon atom is covalently bonded with other carbon atoms.
So the four outermost electrons, four carbon atoms, are engaged or trapped in the covalent bonds which means that there are no free electrons.
Now as we know electrical conductivity relies on the flow of free electrons as there are no free electrons in the diamond so diamond is a bad conductor of electricity.
So diamond is a bad conductor of electricity.
Now unlike most electrical insulators diamond is a good conductor of heat because of strong covalent bonding and low photon scattering.
Thermal conductivity of natural diamond was measured to be about 2200W / (m. k), which is five times more than the silver, the most thermally conductive metal.
So diamond is a good conductor of heat.
So the given statement is true.

Hence option (A) is the correct answer.

Note – Diamond is a crystal structure in a FCC (face centered cubic) lattice. Each carbon atom joins other four carbon atoms in a regular tetrahedron shape that is a type of triangular prisms. The carbon atoms are located at the center and 4 apiece of each tetrahedron. We have heard that diamond is the hardest element that happens due to intensive covalent bonding.