An ore of tin containing $FeCrO_4$ is concentrated by

Which substance is used as a froth stabilizer in the froth flotation process?

In the extraction of $Al$,the chemical used in the $Serpek$ process during leaching is:

In the froth floatation process for the purification of ores,the ore particles float because

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:

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: