Zone refining: Ultra pure Ge

- Zone refining is a method used to obtain ultra-pure materials by removing impurities from a solid material.
- In this process, a rod of the material is passed through a high-temperature zone created by an induction heater.
- As the rod passes through the high-temperature zone, impurities with lower melting points migrate towards one end of the rod, forming a molten zone.
- The molten zone is then moved along the rod, thereby leaving behind a purified solid material.
- This process is repeated several times to obtain a highly purified material.
- In the given option, zone refining is correctly matched with ultra-pure Ge (germanium).

Mond's process: Pt

- Mond's process is a method used for the purification of nickel.
- In this process, impure nickel is reacted with carbon monoxide gas at high temperatures to form volatile nickel tetracarbonyl.
- The volatile nickel tetracarbonyl is then heated to a higher temperature, causing the decomposition of the compound and the recovery of pure nickel.
- The impurities present in the nickel do not form volatile compounds and are left behind as residues.
- In the given option, Mond's process is incorrectly matched with Pt (platinum).

Cupellation: Ag

- Cupellation is a process used for the purification of precious metals, especially silver.
- In this process, the impure metal is heated in a stream of air or oxygen, causing the impurities to oxidize and form slag.
- The slag is then removed, leaving behind purified metal.
- Cupellation is commonly used for the purification of silver, as it selectively oxidizes impurities such as lead, zinc, and copper while leaving silver unaffected.
- In the given option, cupellation is correctly matched with Ag (silver).

Poling: Cu

- Poling is a process used for the purification of copper.
- In this process, impure copper is melted and stirred with green logs of wood.
- The oxygen present in the wood reacts with impurities such as iron and sulfur, forming oxides and sulfides that can be easily removed.
- The impurities are converted into a scum that floats on the surface of the molten copper, allowing for their separation.
- In the given option, poling is correctly matched with Cu (copper).

Therefore, the correctly matched options are A (Zone refining: Ultra pure Ge), C (Cupellation: Ag), and D (Poling: Cu).