During the electrolytic reduction of alumina,two auxiliary electrolytes $X$ and $Y$ are added to increase the electrical conductance and lower the melting point of the mixture. $X$ and $Y$ are:

Extraction of metal from the ore cassiterite involves

Which of the following statements is not correct?
$1$. Reduction of alumina to give aluminium by magnesium is thermodynamically feasible.
$2$. The point of intersection of $Al_2O_3$ and $MgO$ curves in Ellingham diagram is below $1665 \ K$.
$3$. Use of magnesium as reducing agent in metallurgy of aluminium is economical.
$4$. Ellingham diagram represents the graphical plot of Gibbs energy vs temperature for the formation of the oxides of common metals and reducing agents.

In the metallurgical extraction of copper,the following reaction is used:
$FeO + SiO_{2} \rightarrow FeSiO_{3}$
$FeO$ and $FeSiO_{3}$ respectively are:

Impure silver ore $+ CN^{-} + H_2O \xrightarrow{O_2} [X]^{-} + OH^{-}$
$[X]^{-} + Zn \longrightarrow [Y]^{2-} + Ag \text{ (pure)}$
The coordination numbers of the metals in $[X]$ and $[Y]$ are respectively

Which of the following is $NOT$ an extraction process for silver?