$A$ metal has a high concentration in the Earth's crust and its oxides cannot be reduced by carbon. The most suitable method for the extraction of such metal is:

The Ellingham diagram of a certain metal $M$ is represented in the figure. The points $A$ and $B$ respectively correspond to:

In the extraction of silver by the Mac-Arthur-Forrest cyanide process,a small amount of $KNO_3$ is also added as a flux. The function of $KNO_3$ is

Among the following,the main reactions occurring in the blast furnace during the extraction of iron from haematite are:
$i$. $Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2$
$ii$. $FeO + SiO_2 \rightarrow FeSiO_3$
$iii$. $Fe_2O_3 + 3C \rightarrow 2Fe + 3CO$
$iv$. $CaO + SiO_2 \rightarrow CaSiO_3$

Aluminium is used as a reducing agent in the reduction of

Pure $O_2$ instead of air is used to oxidise the pig iron because