Question

Consider the following metallurgical processes:

(I) Heating impure metal with $CO$ and distilling the resulting volatile carbonyl (b.p. ${43}^{\circ }C$) and finally decomposition at $150-{200}^{\circ }C$ 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 metal sulphide.

(III) Electrolysis of the molten electrolyte containing approximately equal amounts of the metal chloride and $NaCl$ to obtain the metal.

The processses used for obtaining Mg, Ni and Cu are respectively:

• A. (I), (II) and (III)
• B. (II), (III) and (I)
• C. (III), (I) and (II)
• D. (II), (I) and (III)

Answer 1

The correct option is C (III), (I) and (II)

(I) $\underset{\left(impure\right)}{Ni}+4CO\stackrel{{50}^{\circ }C}{\to }\underset{\left(volatile\right)}{\left[Ni\right(C{O}_4\left)\right]}\stackrel{{230}^{\circ }C}{\to }\underset{\left(pure\right)}{Ni}+4CO\uparrow$

(II) $C{u}_{2}S+\frac{3}{2}{O}_2\stackrel{\Delta }{\to }C{u}_{2}O+S{O}_2$
$C{u}_{2}S+2C{u}_{2}O\underset{temp.}{\overset{high}{\to }}6Cu+S{O}_2$

(III) $MgC{l}_2\left(s\right)\stackrel{electrolysis}{\to }M{g}^{2+}\left(aq\right)+2C{l}^{-}\left(aq\right)$
$\text{At cathode:}M{g}^{2+}\left(aq\right)+2e^{-}\to Mg\left(s\right)$
$\text{At anode:}2C{l}^{-}\left(aq\right)\to C{l}_2\left(g\right)+2e^{-}$