Which method is used for the concentration of the tin ore containing $FeCrO_4$?

Which method is used for the concentration of the ore containing iron chromate $(FeCrO_4)$?

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

Which principle is involved in magnetic separation?

Leaching is commercially carried out for the concentration of which of the following ores?

Select the correct option regarding the method of separating two sulfide ores by the froth flotation process.
$(1)$ The ratio of water and oil is chosen appropriately.
$(2)$ Some depressants are used for this process.
$(3)$ $HCN$ is a depressant for a mixture of $ZnS$ and $PbS$.
$(4)$ By using a suitable depressant for a mixture of $ZnS$ and $PbS$,only $PbS$ comes up with the froth.