Which process is used for the extraction of copper from low-grade copper ores?

Among the following groups of oxides,the group containing oxides that cannot be reduced by $C$ to give the respective metal is

Extraction of aluminium from bauxite ore,reduction is carried out by

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: In the Ellingham diagram,a sharp change in slope of the line is observed for $Mg \rightarrow MgO$ at $\sim 1120^{\circ} C$.
Reason $R$: There is a large change of entropy associated with the change of state.
In the light of the above statements,choose the correct answer from the options given below.

In the extraction of which of the following,a complex ion is formed?

The flux used to remove the $FeO$ impurity present in the mixture obtained from the roasting of copper pyrites,and its nature,is .....