Column-I and Column-II contains four entries each. Entries of column-I are to be matched with some entries of column-II. Each entry of column-I may have the matching with one or more than one entries of column-II.

Answer

A, B, C, D

Explanation

Poling : Impure molten metal is stirred with green wood poles, oxide impurities are removed, mainly used for Cu and Sn.
Cupellation is used when impurities are of other metals, mainly used for silver.
Electro-refining : Cu,Ag,Au,Cr,Zn,Ni,etc., are mainly purified by removing insoluble impurities as anode mud.
van Arkel method : (vapour phase refining) Metals like titanium, zirconium, thorium and uranium are purified by this method.