How does an intrinsic semiconductor behave at $0 \ K$?

At $0 \ K$ temperature,the valence band in semiconductors is .....

$A$ piece of copper and another of germanium are cooled from room temperature to $80\, K$. The resistance of :-

In the energy band diagram of insulators,the band gap and the conduction band are respectively:

Read the following statements carefully:
$Y:$ The resistivity of a semiconductor decreases with an increase in temperature.
$Z:$ In a conducting solid,the rate of collision between free electrons and ions increases with an increase in temperature.
Select the correct statement from the following:

Carbon,silicon and germanium have four valence electrons each. At room temperature,which one of the following statements is most appropriate?