1.

Extraction of gold (Au) involves the formation of complex ions 'X' and 'Y. Gold ore overset("Roasting")underset(CN^(-),H_(2)O,O_(2))to HO^(-)+X overset("Zn")to Y+Au 'X' and 'Y' are respectively

Answer»

`Au(CN)_(2)^(-)` and `ZN(CN)_(4)^(2-)`
`Au(CN)_(3)^(-)` and `Zn(CN)_(6)^(4-)`
`Au(CN)_(3)^(-)` and `Zn(CN)_(6)^(4-)`
`Au(CN)_(4)^(-)` and `Zn(CN)_(3)^(-)`

SOLUTION :`4Au_((s))+8CN_((aq))^(-)+2H_(2)O_((l))+O_(2(g))+O_(2(g))rarr 4[Au(CN)_(2)]_((aq))^(-)+4OH_((a))^(-)`
`2[Au(CN)_(2)]_((aq))^(-)+Zn_((s))rarr 2Au_((s))+[Zn(CN)_(4)]_((aq))^(2-)`


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