What is the band gap energy for an insulator in $eV$?

Would there be any advantage to adding $n$-type or $p$-type impurities to copper?

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

Pure sodium $(Na)$ is a good conductor of electricity because the $3s$ and $3p$ atomic bands overlap to form a partially filled conduction band. By contrast,the ionic sodium chloride $(NaCl)$ crystal is:

The resistivity of a semiconductor depends upon

Match the List $I$ with List $II$:

$LIST$ $I$	$LIST$ $II$
$A$. Intrinsic Semiconductor	$I$. Fermi-level near conduction band
$B$. $n$-type semiconductor	$II$. Fermi-level at middle
$C$. $p$-type semiconductor	$III$. Fermi-level near valence band
$D$. Metals	$IV$. Fermi-level inside conduction band

Choose the correct answer from the options given below: