Van arkel method is generally used for

$(a)\;\text{zinc} \\(b)\;\text{Zirconium} \\(c)\; \text{Cromium} \\ (d)\; \text {Cobalt}$

Solution :
This method is very useful for preparing ultra - pure metals by removing all oxygen and nitrogen present in form of impurity in certain metals like Zr and Ti.
In this , crude Zr, or Ti is heated in evacated vessel with iodine .
The volatile $Zrl_4$ or $Til_4$ formed is separated and is then decomposed by heating over tungsten filament to give pure Zr or Ti
edited Mar 30