In the purification of bauxite by Hall's process:

The ore that is concentrated by froth floatation process is

Bauxite ore is concentrated by

Depressant used in the concentration of an ore containing $ZnS$ and $PbS$ is

Observe the following statements regarding the purification of bauxite:
$I$. During Hall's process,silica is removed as $Si$ (vapour).
$II$. Bauxite ore contaminated with $Fe_2O_3$ is purified in Baeyer's process.
$III$. During Serpeck's process,$AlN$ is formed.
The correct answer is:

In the leaching method,bauxite ore is digested with a concentrated solution of $NaOH$ that produces $X$. When $CO_2$ gas is passed through the aqueous solution of $X$,a hydrated compound $Y$ is precipitated. $X$ and $Y$ respectively are