Ores like magnetite or tungstates in tin ores are concentrated by

Cassiterite is 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.

Magnetic separation method is applicable for the concentration of which of the following ores?

Which oil is used in the froth flotation process for the concentration of ores?

What are the various methods used for the concentration of an ore?