In which material is the energy band gap maximum?

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

Choose the correct statement. In conductors,

If $V_0$ is the volume of a standard unit cell of germanium crystal containing $N_0$ atoms,then the expression for the mass $m$ of a volume $V$ in terms of $V_0, N_0, M$ and $N_A$ is [here,$M$ is the molar mass of germanium and $N_A$ is the Avogadro's constant].

$A$ piece of copper and a piece of germanium are cooled from room temperature to $80 \text{ K}$. Then, which one of the following is correct?

When radiation with a wavelength shorter than $2480 \, nm$ is incident on a semiconductor,its conductivity increases. The bandgap of this semiconductor is ....... $eV$.