Froth floatation process is used for the concentration of the ore of

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

Which of the following statements is not correct?
$(i)$ Froth-floatation is used for removing gangue from sulphide ore.
$(ii)$ Cresols are used to stabilise the froth.
$(iii)$ Sodium cyanide can be used as depressant for preferential separation.
$(iv)$ Aniline can be used as froth enhancer.

$PbS$ can be separated from $ZnS$ by electrostatic separation. Which property is involved in this method?

The froth flotation process used for the concentration of sulphide ore:

What is the role of a depressant in the froth flotation process?