In the leaching of alumina from bauxite, the ore expected to leach out in the process by reacting with $\mathrm{NaOH}$ is:

The process of the isolation of a metal by dissolving the ore in a suitable chemical reagent followed by precipitation of the metal by a more electropositive metal is called:

Carbon and $CO$ gas are used to reduce which of the following pairs of metal oxides for extraction of metals ?

Impure aluminium is purified by

Among the following statements, the incorrect one is