A. Mg in solid state show electronic condutivity due to preseence of free electrons hence , they are known as electrons conductors.
B. ` MgCl_(2)` in mothen state .
C. Silicon doped with phosphorus contain one extra due to which it shows conductivity under the influence of electric field and known as p- type semiconductor .
D. Germanium doped with boron contain one hole due to which it shows conductivity under the influence of electric field and known as n-type semiconductor .