An ore like zinc blende is concentrated by

For the purification of alumina,the modern processes most useful when $(i)$ the impurity present is a lot of iron oxides and $(ii)$ the impurity present is a lot of silica,are:

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

An ore of tin containing $FeCrO_4$ is concentrated by

Froth flotation method is used for the concentration of $.......$.

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 :