Consider the following metallurgical processes: a. Heating impure metal with CO and distilling the resulting volatile carbonyl BP 43∘C and finally decomposing at 150°C  to 230∘C to get the pure metal b. 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 sulphidec. Electrolysing the molten electrolyte containing CaCl2 to obtain the metalThe processes used for obtaining sodium, nickel, and copper ate, respectively

Electrolyzing the molten electrolyte (NaCl) containing CaCl2​ to obtain sodium metal in Down's method. The mixture CaCl2​+KF lowers the melting point of NaCl from 800oC to 6000C. Sodium is obtained at the cathode which is an iron rod. The anode is graphite rod.Heating impure metal with CO and distilling the resulting volatile carbonyl (b.pt. 43∘C) and finally decomposing at 150∘C to 230∘C to get the pure nickel metal.Heating the sulphide ore in the air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged sulphide to form copper metal.2Cu2​S+3O2​→2Cu2​O+2SO2​2Cu2​O+Cu2​S→6Cu+SO2​This is an example of auto reduction and the process is called Bessemerization.The processes used for obtaining sodium, nickel and copper are c, a, and b respectively.