46. Match the items of Column I with items of Column II and assign the correct code:

Column I	Column II
(A) Pendulum	(1) Chrome steel
(B) Malachite	(2) Nickel steel
(C) Calamine	(3) Na3AlF6
(D) Cryolite	(4) CuCO3⋅Cu(OH)2
	(5) ZnCO3

Code:

A (1) B (2) C (3) D (4)

A (2) B (4) C (5) D (3)

A (2) B (3) C (4) D (5)

A (4) B (5) C (3) D (2)

 $\frac{dE}{dT}$ is the temperature Co-efficient of cell. The cell having less variation of EMF, with respect to temperature have high efficiency.

Below 1350° C, Mg can reduce Al₂O₃ and above 1350°C, Al can reduce MgO (from Ellingham diagram).

Melting and boiling point of Mg are lower than that of Al.

In ores/mineral available earthy and undesired impurities are gangue

Sol. Reactivity towards ${\mathrm{A}\mathrm{g}\mathrm{N}\mathrm{O}}_3$  depend on stability of carbocation formed

Leaching involves the given reaction,

$4Au\left(s\right)+8C{N}^{-}\left(aq\right)+2H_{2}O\left(aq\right)+O_2\left(g\right)\to 4{\left[Au{\left(CN\right)}_2\right]}^{-}\left(aq\right)+4O{H}^{-}\left(aq\right)$              

Here, O₂ is required for formation of Au (l) cyanide complex but no complex in absence of O₂.

$2{\left[Au{\left(CN\right)}_2\right]}^{-}\left(aq\right)+Zn\left(s\right)\to {\left[Zn{\left(CN\right)}_4\right]}^{2-}\left(aq\right)+2Au\left(s\right)$                

In above displacement reaction, Zn is oxidized.