Amorphous solids are

Which one of the following elements on doping with germanium, makes it a $p$-type semiconductor?

$A$ group $14$ element is to be converted into $n-$type semiconductor by doping it with a suitable impurity. To which group should this impurity belong?

$A$ solid is hard and brittle. It is an insulator in solid state,but conducts electricity in molten state. The solid is a

Classify the following materials into superconductors,conductors,semiconductors,and insulators: $Cu$,$Al$,$Si$,$Ge$,glass,Teflon,$Au$,$Pt$,$CuO$ (at low temperature),graphite,carbon black,and alloys at low temperature.

What happens when glass is heated?