$CN^{-}$ solution is used in the extraction of which metal?

Observe the following Ellingham diagram,and identify the incorrect statement regarding it.

In the extraction of copper,metal is formed in the Bessemer converter due to the reaction:

The function of the flux added during smelting is

The main reactions occurring in a blast furnace during the extraction of iron from haematite are $....$.
$(i)$ $Fe_2O_3 + 3CO \to 2Fe + 3CO_2$
$(ii)$ $FeO + SiO_2 \to FeSiO_3$
$(iii)$ $Fe_2O_3 + 3C \to 2Fe + 3CO$
$(iv)$ $CaO + SiO_2 \to CaSiO_3$

Which is the main reducing agent for extraction in a blast furnace?