Name the metal $M$ which is extracted on the basis of following reactions:
$4M + 8CN^{-} + 2H_2O + O_2 \rightarrow 4[M(CN)_2]^{-} + 4OH^{-}$
$2[M(CN)_2]^{-} + Zn \rightarrow [Zn(CN)_4]^{2-} + 2M$

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.

Ellingham diagram is the plot of $X$ vs $Y$. What are $X$ and $Y$?

To prevent magnesium from oxidation in the electrolytic extraction process,which of the following is done?

Consider the following metallurgical processes:
$(i)$ Heating impure metal with $CO$ and distilling the resulting volatile carbonyl (boiling point $43\,^{\circ}C$) and finally decomposing at $150\,^{\circ}C$ to $200\,^{\circ}C$ to get the pure metal.
$(ii)$ Heating the sulphide ore in air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged sulphide.
$(iii)$ Electrolysing the molten electrolyte containing approximately equal amounts of the metal chloride and $CaCl_2$ to obtain the metal.
The processes used for obtaining sodium,nickel and copper are,respectively,

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: In the Ellingham diagram,a sharp change in slope of the line is observed for $Mg \rightarrow MgO$ at $\sim 1120^{\circ} C$.
Reason $R$: There is a large change of entropy associated with the change of state.
In the light of the above statements,choose the correct answer from the options given below.