Among the following, the main reactions occurring in blast furnace during extraction of iron from haematite are

(i) $$\mathrm{Fe}_2 \mathrm{O}_3+3 \mathrm{CO} \rightarrow 2 \mathrm{Fe}+3 \mathrm{CO}_2$$

(ii) $$\mathrm{FeO}+\mathrm{SiO}_2 \rightarrow \mathrm{FeSiO}_3$$

(iii) $$\mathrm{Fe}_2 \mathrm{O}_3+3 \mathrm{C} \rightarrow 2 \mathrm{Fe}+3 \mathrm{CO}$$

(iv) $$\mathrm{CaO}+\mathrm{SiO}_2 \rightarrow \mathrm{CaSiO}_3$$

Electrolytic refining is used to purify which of the following metals?

The common impurity present in bauxite is

The metal extracted by leaching with a cyanide is