The substance added in water in the froth floatation process is

Which soluble substances are obtained when bauxite is treated with a solution of $NaOH$ at a temperature of $473 - 523 \ K$ and a pressure of $35 - 36 \ bar$?

Wolframite ore is separated from tinstone $(SnO_2)$ by which of the following processes?

Which of the following is used as a depressant in the separation of $ZnS$ from $PbS$ in the froth flotation process?

The correct statement is:

Given below are two statements :
Statement $I :$ Sphalerite is a sulphide ore of zinc and copper glance is a sulphide ore of copper.
Statement $II :$ It is possible to separate two sulphide ores by adjusting proportion of oil to water or by using 'depressants' in a froth flotation method.
Choose the most appropriate answer from the options given below :