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

The ore of which metal is concentrated by leaching?

Froth flotation process is used for the concentration of:

During initial treatment,preferential wetting of ore by oil and gangue by water takes place in

$NaCN$ is sometimes added in the froth flotation process as a depressant when $ZnS$ and $PbS$ minerals are expected because

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