The correct answer is: B. Zone melting
Zone melting is a method of purifying a semiconductor or other material by melting a small section of the material and then allowing it to refreeze. This process is repeated many times, with the molten zone moving along the length of the material. As the molten zone moves, impurities are left behind in the solid material. This process can be used to purify metals, semiconductors, and other materials to very high levels.
Slugging is a process of adding a small amount of a pure metal to a molten metal to improve its properties. The slugging metal is usually a metal that has a higher melting point than the base metal. When the slugging metal is added to the molten metal, it forms a layer on the surface of the molten metal. This layer helps to protect the base metal from oxidation and other contaminants.
Smelting is a process of extracting a metal from its ore. The ore is heated until it melts, and then the metal is separated from the other materials in the ore. Smelting is a very energy-intensive process, and it can produce a lot of pollution.
Leaching is a process of dissolving a substance from a solid material. The solid material is placed in a solution, and the substance is dissolved in the solution. Leaching is often used to extract metals from ores.
In conclusion, the correct answer to the question “Ultra purification of a metal is done by:” is B. Zone melting.