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

In the froth floatation process for the concentration of ores,the ore particles float because:

Sulphide ores are generally concentrated by

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.

The methods $NOT$ involved in the concentration of ore are:
$A$. Liquation
$B$. Leaching
$C$. Electrolysis
$D$. Hydraulic washing
$E$. Froth flotation
Choose the correct answer from the options given below:

Bauxite ore is concentrated by