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

The ore of which metal is concentrated by leaching?

Which of the following ores is concentrated by the froth flotation process?

An ore of tin containing $FeCrO_4$ is concentrated by

Which of the following reactions is suitable for concentrating ore by the leaching process?

For the purification of alumina,the modern processes most useful when $(i)$ the impurity present is a lot of iron oxides and $(ii)$ the impurity present is a lot of silica,are: