The ore that is concentrated by the froth floatation process is

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.

In metallurgy,the term "gangue" is used for:

The process of ore dressing is carried out to

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

The beneficiation of the sulphide ores is usually done by