The substance added to the ore to remove impurities is known as........

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 of the following ores is best concentrated by the froth-flotation method?

Which step is involved in the extraction of $Pb$ from galena $(PbS)$?

Observe the following statements regarding the purification of bauxite:
$I$. During Hall's process,silica is removed as $Si$ (vapour).
$II$. Bauxite ore contaminated with $Fe_2O_3$ is purified in Baeyer's process.
$III$. During Serpeck's process,$AlN$ is formed.
The correct answer 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 :-