Froth flotation method is used for the concentration of which type of ores?

The purification of alumina is called

The pair of oxides,which can be leached out when powdered bauxite containing certain impurities is digested with a concentrated solution of $NaOH$ at $473-523 \ K$ temperature and $35-36 \ bar$ pressure,are:

Froth-floatation method is successful in separating impurities from ores because

What is the significance of leaching in the extraction of aluminium?

Which of the following ores can be concentrated by the froth flotation method?