Q1: Which semiconductor material is made from coal ash?

ANS:A - germanium

Coal fly ashes might be expected to be rich in germanium. They are extracting Germanium from Coal fly ash.

Ancient processes caused Germanium to become somewhat concentrated in certain Coal seams, and, once the Carbon has been combusted for whatever purpose, the Ash from that Coal contains recoverable Germanium in concentrations higher than the Lead and Zinc ores from which it is currently being produced.