The idea of the froth floatation method came from a person $X$ and this method is related to the process $Y$ of ores. $X$ and $Y$,respectively,are

Chemical leaching is useful in the concentration of

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

Which of the following is not concentrated by electromagnetic separation?

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.

Electromagnetic separation is used in the concentration of