Consider the following metallurgical processes: (I) Heating impure metal with CO and distilling the resulting volatile carbonyl (b.p. 430C) and finally decomposition at 1500-2000C to get the pure metal (II) Heating the sulphide ore in air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged metal sulphide (III) Electrolysis of the molten electrolyte containing approximately equal amounts of the metal chloride and NaCl to obtained the metal The processes used for obtaining magnesium nickel and copper are respectively: