Which of the following methods is $NOT$ used for the refining of impure metals in metallurgy?

In the electrolytic refining of metals,the electrolysis of an aqueous solution of its complex salt is performed using an impure metal as the anode and a strip of pure metal as the cathode. This method cannot be used for the refining of which of the following metals?

What is the composition of the anode mud in the electrolytic refining of silver?

Which of the following is not correctly matched?

During the purification of an impure metal by electrolysis,the impure metal is used as the ...... and the pure metal is used as the ...... .

Match the refining methods (Column $I$) with metals (Column $II$).

Column $I$ (Refining methods)	Column $II$ (Metals)
$(I)$ Liquation	$(a)$ $Zr$
$(II)$ Zone refining	$(b)$ $Ni$
$(III)$ Mond process	$(c)$ $Sn$
$(IV)$ Van Arkel Method	$(d)$ $Ga$