Answer the following questions:
What is the role of collectors in the froth floatation process? Give an example of a collector.

If the percentage of $Fe$ in the ore (as nearest integer value) is $6X+1$. Then $X$ is:

(i) What is the actual reducing agent of haematite in blast furnace?
(ii) Give the equations for the recovery of lead from galena by air reduction
(iii) Why is sodium chloride added during electrolysis of fused anhydrous magnesium chloride?
(iv) Zinc, not copper, is used for the recovery of metallic silver from the complex $[Ag(CN{)}_2{]}^{-}$, explain.
(v) Why is chalcocite roasted and not calcinated during recovery of copper?