Choose the only false statement from the following
Substances with energy gap ofthe order of 10 eV are insulators
The conductivity of a semiconductor increases with increases in temperature
In conductors the valence and conduction bands may overlap
The resistivity of a semiconductor increases with increase in temperature
D.
The resistivity of a semiconductor increases with increase in temperature
(a) In insulators energy gap is of the order of 5 to 10 eV and it is practically impossible to impart this much amount of energy to the electrons in valence band. So, as to jump to conduction band. So, choice (a) is correct.
(b) In semiconductors with the rise in temperature more electrons from valence band jump to conduction band and this results is increase in conductivity. So, choice (b) is correct.
(c) In conductors, the conduction band is either partially filled or the conduction band overlaps on the valence band. So, choice (c) is correct.
(d) In semiconductor, resistivity decreases with increase in temperature. So, choice (d) is wrong.