a) For silicon, if EG decreases by 0.078 eV, by what fraction does n; increase (assume T is constant at 300K)? b) If the temperature rises from 300K to 600K, by what additional fraction does n; increase (assume EG is constant = 1.068 eV, you do not need to worry about the decrease from problem a)? c) If we further increase the temperature, Si starts exhibiting semi-metal properties. Think of a physical reason for this phenomenon. (Assume you haven't melted it).