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Cu^(2+) and Cd^(2+) are separated by fir...

`Cu^(2+)` and `Cd^(2+)` are separated by first adding KCN solution and then passing `H_(2)S` gas.
KCN reduces `Cu^(2+)` to `Cu^(+)` and forms a complex with it.

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The correct Answer is:
B
The correct explanation of assertion is KCN complex with `Cu^(+)` and `Cd^(2+)` as `K_(3)[Cu(CN)_(4)]` and `K_(2)[Cd(CN)_(4)]` respectively. On passing `H_(2)S` only `Cd^(2+)` complex gets decomposed to yellow Cds ppt.
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Coordination compounds plays many important roles in animals and plants. The are essential in the storage and transport of oxygen as electrons transfer agents as catalysts and in photosynthesis Wide range of application in daily life takes place through formation of complexes Photographic fixing qualitative and quantitative analysis purification of water metallurgical extraction are some specific worth mentioning Cu^(2+) and Cd^(2+) both are precipitated as sulphides on passing H_(2)S gas in dil HCI medium However, precipitation of Cu^(2+) is prevented by (a) Adding excess of K_(4)[Fe(CN)_(6)] when Cd^(2+) is only precipitated (b) Adding excess of KNC when Cu^(2+) for stable complex [Cu(CN)_(4)]^(3-) and Cd^(2+) forms unstable complex [Cd(CN)_(4)]^(2-) (c ) All of the above

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