Name the reagent that is used in leaching of gold.

Which of the following substances acts as a collector in the froth floatation method?

The ore that is concentrated by froth floatation process is

Which of the following ores is concentrated using a group $1$ cyanide salt?

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 :

Reagent used in Bayer's process of concentration of bauxite ore is: