For a germanium crystal,the forbidden energy gap in joules is:

The intrinsic semiconductor becomes an insulator at

In good conductors of electricity,the type of bonding that exists is

At $0 \ K$,a piece of germanium:

Explain with a diagram how current flows due to electrons and holes in a pure semiconductor.

Carbon,Silicon,and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by $(E_g)_C$,$(E_g)_{Si}$,and $(E_g)_{Ge}$ respectively. Which one of the following relationships is true in their case?