When aqueous solution of potassium fluoride is added to the blue coloured aqueous `CuSO_(4)` solution , a green precipitate is formed . This observation can be explained as follows .

Options

A. On adding `KF , H_(2)O` being weak field ligand is replaced by `F^(-)` ions forming `[CuF_(4)]^(2-)` which is green in colour .
B. Potassium is coordinated to `[Cu(H_(2)O)_(4)]^(2+)` ion present in `CuSO_(4)` and gives green colour .
C. On adding `KF , Cu^(2+)` are replaced by `K^(+)` forming a green complex .
D. Blue colour of `CuSO_(4)` and yellow colour of KI form green colour on mixing .

Answer

A

Explanation

Aqueous `CuSO_(4)` solution contains `[Cu(H_(2)O)_(4)]^(2+)` ions which are blue in colour . When aqueous solution of KF is added , `H_(2)O` being weak field ligand can be replaced by `F^(-)` ions forming `[CuF_(4)]^(2-)` which is green in colour .
`[Cu(H_(2)O)_(4)]^(2+) underset(( "from" KF)) (+4F^(-)) to underset("Green")([CuF_(4)]^(2-)) + 4 H_(2)O`