Explain the role of the following:

(a) NaCN in the separation of ZnS and PbS.

(b) `SiO_2` in the metallurgyof Cu containing Fe as impurity.

(c) Iodine in the refining of Ti.

Explain the role of each of the following : (i) NaCN in the extraction of silver (ii) SiO_(2) in the extraction of copper

Mention the role of following : (a) SiO_2 in the metallurgy of Cu. (b) CaCO_3 in the metallurgy of Fe. (c) CO in the metallurgy of iron. (d) I_2 in the purification of zirconium.

What is the role of the following compounds : (a) CaF_(2) in the metallurgy of aluminium ? (b) SiO_(2) in the extraction of copper from copper pyrites ?

Which of the following is a representative element? (A) Zn (B) Sr (C) Cu (D) Fe

Which of the following reagents willnot be useful in separating a mixture of Zn^(2+) and Cu^(2-) ?

Lead obtained form galena (PbS) by air reduction or carbon reduction process contains base metal (Cu, Bi, Sn, As) as impurities, due to the which lead becomes hard and brittle. Zn-Ag alloy formed in the upper layer of molten lead is skimmed off from the surface of the molten lead by perforated ladles. This alloy contains lead as impurity. This impurity of Pb is removed by

(a) Which of the following metals cannot be extracted by the smelting process ? Al, Zn, Fe and Pb . (b) Graphide is used as anode but not diamond. Give reason. ( c) Give a method for separation of nickel from cobalt ?