During metallurgy, the metal extracted may still contain impurities. Different methods are used to obtain pure metal from the cude sample based on the nature of the impurities present. Suggest a method for refining crude tin metal. Justify your answer.

You are given conc. HCl and salts of some alkaline earth metals and directed to conduct flame test and to detect the cation present in each salt. (a) Can you detect all the cations which are given here by this method? [CaCl_2, MgSO_4, Ba(NO_3)_2, BeCl_2, SrCl_2] (b) Justify your answer. (c) What is the mechanism of this test?

In electrolytic refining of metals, the impure metal is made, the anode and a strip of pure metal,the cathode during the,electrolysis of an aqueons solution of a complex metal salt. This method cannot be used for refining of : silver, copper, aluminium, zinc

Consider the following metallurgical processes in 1. Heating impure metal with CO and distilling the resulting volatile carbonyl boiling point 43^@C and finally decomposing at 150^@ to 200^@C 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 sulphide. III. Electrolysing the molten electrolyte containing approximately equal amounts of the metal chloride and CaCl_2 to obtain the metal. The processes used for obtaining sodium, nickel and copper are respectively