When excess of aqueous KCN solution is added to an aqueous solution of copper sulphate , the complex `[Cu(CN)_(4)]^(2-)` is formed . On passing `H_(2)S` gas through this solution no precipitate of CuS is formed because

Options

A. sulphide ions cannot replace `CN^(-)` ions
B. `[Cu(CN)_(4)]^(2-)` does not give `Cu^(2+)` ion in the solution
C. sulphide ions from `H_(2)S ` do not form complexes
D. sulphide ions cannot replace sulphate ions from copper sulphate solution .

Answer

B