In the case 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:

Why does the resistivity of a semiconductor decrease with an increase in temperature?

In semiconductors at room temperature,

$C$ and $Si$ both have the same lattice structure,having $4$ bonding electrons in each. However,$C$ is an insulator whereas $Si$ is an intrinsic semiconductor. This is because:

Explain the crystalline structure by writing the electronic configuration of elementary semiconductors.