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

In the extraction of $Al$,the chemical used in the $Serpek$ process during leaching is:

The froth floatation process used for the concentration of sulphide ore:

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.

Haematite ore is concentrated by

What is the product formed when bauxite ore is treated with sodium hydroxide?