Question

$(A+Ag)+Zn⟶(A+Ag+Zn)\stackrel{\text{cooling}}{\to }\frac{x-\text{layer}}{y-\text{layer}}$
$x$ layer - solid alloy $y$ layer - molten metal

Metal A is :

• A. $Cu$
• B. $Sn$
• C. $Fe$
• D. $Pb$

Answer 1

The correct option is D $Pb$

Parke's process is used for the desilverization of argentiferous lead $(PbS+0.01$ to $1$% $Ag)$ and is based on distribution principle as molten zinc and molten lead form a two phase system. Silver is more soluble in molten zinc than in molten lead. The $Zn-Ag$ alloy is lighter and hence forms the top layer $\left(layerX\right).$ The $Pb-Ag$ alloy is heavier and forms the bottom layer $\left(layerY\right).$ The two layers are immiscible and hence the floating solidified $Zn-Ag$ alloy can be easily removed from molten $Pb.$ Thus metal A is $Pb$.