(i)-d , (ii)-c , (iii)-b , (iv)-a

(i) Mg in solid state shows electronic conductivity due to presence of free electrons, hence it is known as electronic conductors.

(ii)MgCl₂ shows electrolytic conductivity in molten state due to presence of electrolytes (Mg²⁺ and Cl^-), thus shows electrolytic conductivity.

(iii) When silicon is doped with phosphorus which contains 5 electrons. 4 electrons are used in bonds and 1 electron left delocalized and thus shows conductivity in electric field. Since the conductivity is due to electron which is negatively charged it is called N type semiconductor.

(iv) When germanium is doped with boron which contains 3 electrons, it generates one hole due to lack of electron. This hole acts as a positive charge and helps in conductivity when placed in electric field. Since the conductivity is due to positive charge it is called P type semiconductors.