Which among the following is used as flux in the extraction of iron from oxide ores?

In the manufacture of iron,limestone is added to the blast furnace. The calcium ion ends up in the form of:

When bauxite powder is mixed with coke and reacted with nitrogen at $2075 \ K$,carbon monoxide and $X$ are formed. What is the gas formed when $X$ is reacted with water?

$A$ complex is formed in the extraction of which of the following metals?

Extraction of copper from copper pyrites is done by heating in a blast furnace. On which principle is this method based?

Statement $I :$ Leaching of gold with cyanide ion in absence of air $/$ $O_2$ leads to cyano complex of $Au(III)$.
Statement $II :$ Zinc is oxidized during the displacement reaction carried out for gold extraction.
In the light of the above statements,choose the correct answer from the options given below.