In the froth flotation process for the concentration of ores,why do the ore particles float?

Wolframite ore is separated from tinstone $(SnO_2)$ by which of the following processes?

The ore which is purified by the leaching process is

In the process of extracting alumina from bauxite,bauxite is concentrated by $......$.

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

The correct statements regarding the froth floatation method in metallurgy are:
$I$. Used for the purification of sulphide ores
$II$. Used for the roasting of sulphide ores
$III$. It is based on the relative densities of gangue and ore particles
$IV$. It is based on the difference in the wetting properties of gangue and ore particles in frothing agent and water