The order of stability of metal oxides is:

In the extraction of which of the following metals is a complex salt formed?

When compared to $\Delta G^{\circ}$ for the formation of $Al_{2}O_{3}$,the $\Delta G^{\circ}$ for the formation of $Cr_{2}O_{3}$ is

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

Lead is mainly extracted by

Which metal cannot be extracted by the smelting process?