The correct options are
A Leaching : Ag
C Liquation : Sn
D Van Arkel : Zr
A) Leaching is the process of extracting minerals from a solid by dissolving them in a liquid, either in nature or through an industrial process. In the chemical processing industry, leaching has a variety of commercial applications, including separation of metal from ore using acid, and sugar from beets using hot water.(Ag2S+NaCN→Na[Ag(CN)2]+Na2S).
B) Zone melting (or zone refining or floating zone process) is a group of similar methods of purifying crystals, in which a narrow region of a crystal is molten, and this molten zone is moved along the crystal. The molten region melts impure solid at its forward edge and leaves a wake of purer material solidified behind it as it moves through the ingot. The impurities concentrate in the melt, and are moved to one end of the ingot.This technique is also used for the preparation of silicon not stannum.
C) Liquation is a metallurgical method for separating metals from an ore or alloy. The material must be heated until one of the metals starts to melt and drain away from the other and can be collected. This method was largely used to remove lead containing silver from copper, but it can also be used to remove antimony from ore, and refine tin (stannum).
D) Van Arkel process was the first industrial process for the commercial production of pure ductile metallic Zirconium.
Hence options A, C & D are correct.