The chemical that is added to reduce the melting point of the reaction mixture during the extraction of aluminium is

The reactions which occur in a blast furnace at $500-800 \ K$ during the extraction of iron from haematite are:
$(i)$ $3 Fe_2O_3 + CO \rightarrow 2 Fe_3O_4 + CO_2$
$(ii)$ $Fe_2O_3 + 3 C \rightarrow 2 Fe + 3 CO$
$(iii)$ $Fe_3O_4 + 4 CO \rightarrow 3 Fe + 4 CO_2$
$(iv)$ $Fe_2O_3 + CO \rightarrow 2 FeO + CO_2$

The plot shows the variation of $- \ln K_p$ versus temperature for the two reactions:
$M_{(s)} + \frac{1}{2} O_{2(g)} \to MO_{(s)}$ and $C_{(s)} + \frac{1}{2} O_{2(g)} \to CO_{(g)}$
Identify the correct statement.

The chemical composition of the slag formed during the extraction of $Cu$ from copper pyrites is ......

Extraction of lead by reduction methods is done by

Steel contains $.....$ percent of carbon.