The resistivity of a semiconductor depends on $........$.

The state of the energy gained by valence electrons when the temperature is raised or when an electric field is applied is called as:

Consider the following statements regarding a semiconductor:
$(A)$ There are no free electrons at $0 \ K$.
$(B)$ There are no free electrons at any temperature.
$(C)$ The number of free electrons increases with temperature.
$(D)$ The number of free electrons is less than that in a conductor.

State the conductivity of metals and resistivity of insulators.

$A$ solid which is transparent to visible light and whose electrical conductivity increases with temperature is formed by:

Which graph shows correctly the temperature $(T)$ dependence of resistivity $(\varrho)$ of a semiconductor?