The Van Arkel method for the purification of metals involves the conversion of the metal into a .........

Blister copper is refined by stirring molten impure metal with green logs of wood because such wood liberates hydrocarbon gases (like $CH_4$). This process $X$ is called . . . . . . . . . and the metal contains impurities of $Y$ is . . . . . . . . .

Copper sulphate is prepared by blowing a current of air through copper scrap and dilute $H_2SO_4$. Dilute $HNO_3$ is also added:

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	$(d)$ $Ga$

Zirconium is refined by

During the electrolytic refining of silver,the anode mud contains: