The purpose of the stream of air in the leaching process of $Ag_2S$ is to:

Which of the following is an acidic flux?

When a metal is to be extracted from its ore,if the gangue associated with the ore is silica,then

Explain the extraction of iron from its oxide ores.

The flux added in the extraction of iron is

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: