Chemical leaching is useful in the concentration of

Given below are two statements :-
Statement $I$: In froth floatation method,a rotating paddle agitates the mixture to draw air into it.
Statement $II$: Iron pyrites are generally avoided for the extraction of iron due to environmental reasons.
In the light of the above statements,choose the correct answer from the options given below :-

In the extraction of aluminium:
Process $X$: applied for red bauxite to remove iron oxide (chief impurity).
Process $Y$: (Serpeck's process) applied for white bauxite to remove $Z$ (chief impurity).
Then,process $X$ and impurity $Z$ are:

An ore of tin containing $FeCrO_4$ is concentrated by

Reagent used in Bayer's process of concentration of bauxite ore is:

Which of the following reactions is a part of the Bayer's process for the extraction of aluminum?