The substance which is mixed with the ore for the removal of impurities is termed as

Difference in density is the basis of

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

Match the method of concentration of ore in Column $I$ with the ore in Column $II$.

$I$ (Method)	$II$ (Ore)
$(I)$ Magnetic separation	$a. Cu_2S$
$(II)$ Froth flotation	$b. FeCr_2O_4$
$(III)$ Gravity separation	$c. Al_2(SiO_3)_3$

The idea of the froth floatation method came from a person $X$ and this method is related to the process $Y$ of ores. $X$ and $Y$,respectively,are

Observe the following statements regarding the purification of bauxite and select the correct answer.
$(I)$ During the $Hall$ process,silicon is removed in the form of vapor.
$(II)$ Bauxite containing $Fe_2O_3$ impurities is purified by the $Bayer$ process.
$(III)$ $AlN$ is formed during the $Serpeck$ process.