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    				| 1. | 
                                    `CuSO_(4)` when reacts with KCN forms `CuCN` which is insoluble in water. It is soluble in excess of KCN due to the formation of the complex.A. `K_(3)[Cu(CN)_(4)]`B. `K_(3)[Cu(CN)_(4))]`C. `Cu(CN)_(2)`D. `Cu[Kcu(CN)_(4)]` | 
                            
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Answer» Correct Answer - B `CuSO_(4)` reacts with KCN to give a white precipitate of cuprous cyanide and cyanogen gas. The cuprous cyanide dissolves in excess of KCN forming `K_(3)[Cu(CN)_(4)]` `CuSO_(4) + 2KCN to K_(2)SO_(4) + Cu(CN)_(2)` `2Cu(CN)_(2) to 2CuCN + CN - CN` `CuCN + 3KCN to K_(3)[Cu(CN)_(4)]`  | 
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