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

Which one of the following is not a method of concentration of ore?

Chemical leaching is useful in the concentration of

The ore which is concentrated by wetting with oil is:

Given below are two statements :-
Statement $I$: In froth floatation method,a rotating paddle agitates the mixture to draw air into it.
Statement $II$: Iron pyrites are generally avoided for the extraction of iron due to environmental reasons.
In the light of the above statements,choose the correct answer from the options given below :-

What is leaching? Explain with an example.