In the equation $4M + 8CN^{-} + 2H_2O + O_2 \to 4[M(CN)_2]^- + 4OH^{-}$,identify the metal $M$.

The form of iron obtained from blast furnace is

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,

Heating a mixture of $Cu_2O$ and $Cu_2S$ gives:

When bauxite powder is mixed with coke and reacted with nitrogen at $2075 \ K$, carbon monoxide and $X$ are formed. What is the gas formed when $X$ is reacted with water?

The metal extracted by the electrolysis of its fused salt is