Match items of Column I with the items of Column II and assign the correct code:
`{:(ColumnI,ColumnII),((A)"Cyanide process",(1)"Ultrapure Ge"),((B)"Froth Floatation Process",(2)"Dressing of"ZnS),((C)"Electrolytic reduction",(3)"Extraction of Al"),((D)"Zone refining",(4)"Extraction of Au"),(,(5)"Purification of Ni"):}`

Options

A. I-(c ), II-(a), III-(d), IV-(b)
B. I-(d), II-(b), III-(c ), IV-(a)
C. I-(c ), II-(b), III-(d), IV-(a)
D. I-(d), II-(a), III-( c ), IV-(b)

Answer

B

Explanation

(I)`4Au//Ag(s)+8CN^(-)(aq)+2H_2O(aq)+O_2(g) to 4[Au//Ag(CN)_2]^(-)(aq)+4OH^(-)(aq)`
`2[Au//Ag (CN)_2]^(-)(aq)+Zn(s)to2Au//Ag(s)+[Zn(CN)_4]^(2-)(aq)`
(II)This method is based on the fact that gangue and ore particles have different degree of wettability with water and pine oil, the gangue particles are preferentially wetted by water while the ore particles are wetted by oil.
(III)Electrolytic reduction (Hall-Heroult process) :
The purified `Al_2O_3` is mixed with `Na_3AIF_5`(cryolite) or `CaF_2` (fluorspar) which lowers the melting point of the mixture and increases conductivity. The fused matrix is electrolysed. the electrolytic reactions are :
Cathode: `Al^(3+)` ("melt")+`3e^(-) to A(l)`
`C(s)+2O^(2-)("melt")toCO_2(g)+4e^(-)`
(IV) This process is used when metals are reqired in very high purity , for specific application. For example pure Si and Ge are used in semiconductors and hence are purified by this method.Zone refining method is based on the principle that an impure molten metal on gradual cooling will deposit crystals of the pure metal. while the impurities will be left in the remaining part of the molten metal.