Matte is a mixture of .......... .

Flux is used to remove $........$.

Which of the following compounds acts as a flux in the extraction of copper from copper pyrites?

In the commercial electrochemical process for aluminium extraction,the electrolyte used is

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

Given are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Magnesium can reduce $Al_{2}O_{3}$ at a temperature below $1350^{\circ} C$,while above $1350^{\circ} C$ aluminium can reduce $MgO$.
Reason $R$: The melting and boiling points of magnesium are lower than those of aluminium.
In light of the above statements,choose the most appropriate answer from the options given below: