Which of the following ores can be concentrated by the froth flotation method?

Leaching of $Ag_2S$ is carried out by heating it with a dilute solution of

Which of the following is used as a stabilizer during the concentration of sulphide ores?

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 :

Which of the following is not concentrated by electromagnetic separation?

Which method is used for the concentration of the ore containing iron chromate $(FeCrO_4)$?