The concentration of chromite ore $(FeO \cdot Cr_2O_3)$ is done by which of the following methods?

Match the method of concentration of the ore in column $I$ with the ore in column $II$ and select the correct alternate :

$I$	$II$
$X$. Magnetic separation	$a$. $Ag_2S$
$Y$. Froth floatation	$b$. $FeCr_2O_4$
$Z$. Gravity separation	$c$. $Al_2(SiO_3)_3$

In the purification of bauxite by Hall's process:

How do we separate two sulphide ores by the Froth Flotation Method? Explain with an example.

The ore of which metal is concentrated by leaching?

While extracting an element from its ore,the ore is ground and leached with dilute $KCN$ solution to form the soluble product potassium argentocyanide. The element is