Question

$C$ and $Si$ both have the same lattice structures having 4 bonding electrons in each. However, $C$ is an insulator whereas $Si$ is an intrinsic semiconductor. This is because
(a) In the case of $C$ the valence band is not completely filled at absolute zero temperature.
(b) In the case of $C$ the conduction band is partly filled even at absolute zero temperature.
(c) The four bonding electrons in the case of $C$ lie in the second orbit. Whereas in the case of $Si$ they lie in the third.
(d) The four bonding electrons in the case of $C$ lie in the third orbit. Whereas for $Si$ they lie in the fourth orbit.

Answer 1

Lattice structure: A space-filling unit cell that can be tessellated along any axis with no gaps between cells is known as a lattice structure. These structures offer a new way to save weight, energy, and time in modern manufacturing.

Complete answer:
First be understood about electronic configuration: Each electron is described as travelling independently in an orbital in an average field created by all other orbitals in electronic setups.
Configurations are described mathematically by Slater determinants or configuration state functions.
So, we can write
The Electronic configuration of as carbon ( $6C$ ) is $1{s^2}{\text{ }}2{s^2}{\text{ }}2{p^2}$ .
The electronic configuration of silicon ( $14Si$ ) is $1{s^2}\;2{s^2}\;2{p^6}3{s^2}\;3{p^2}.$
So, electrons belonging to ${3^{rd}}$ orbit will be less tightly bound to nuclear force.
Hence they can easily escape or move to and fro and behave as a semiconductor.
We can conclude that the four bonding electrons in the case of C lie in the second orbit. Whereas in the case of Si they lie in the third
So, option (C) is the correct option.

Note:
Semiconductors are used in the production of diodes, transistors, and integrated circuits, among other electronic devices. Because of their compactness, reliability, power efficiency, and low cost, such devices have found widespread use. Silicon, germanium, and gallium arsenide are the most common semiconductor materials. Germanium was one of the first semiconductor materials to be used. Germanium has four valence electrons, or electrons that are placed on the atom's outer shell.