Question

Choose the only false statement from the following

• A. Substances with energy gap of the order of 10 eV are insulators
• B. The conductivity of a semiconductor increases with increases in temperature
• C. In conductors the valence and conduction bands may overlap
• D. The resistivity of a semiconductor increases with increase in temperature

Answer 1

Answer: (D)

The resistivity of a semiconductor increases with increase in temperature

Answer 2

It is nearly hard to give electrons in the valence band enough energy to jump to the conduction band since the energy gap in insulators is of the order of 5 to 10 eV.
More electrons from the valence band of semiconductors jump into the conduction band when the temperature rises, increasing conductivity. In conductors, the conduction band either overlaps the valence band or is just partially filled.
The resistance of semiconductors reduces as temperature rises.

So, option (D): The resistivity of a semiconductor increases with increase in temperature is the only false statement.