Aqueous copper sulphate solution (blue in colour) gives:
(i). A green precipitate with aqueous potassium fluoride and
(ii). A bright green solution with aqueous potassium chloride. Explain these experimental results.

Explanation

Aqueous `CuSO_(4)` solution exists as `[Cu(H_(2)O)_(4)]SO_(4)` which has blue colour due to `[Cu(H_(2)O)_(4)]^(2+)` ions
(i) When KF is added the weak `H_(2)O` ligands are replaced by `F^(-)` ligands forming `[CUF_(4)]^(2-)` ions which is a green precipitate
`[Cu(H_(2)O)^(2+)+4F^(-)rarrunderset("tetrafluridocuprate(II)")[CuF_(4)]^(2-)+4H_(2)O`
(ii) When KCl is added `Cl^(-)` ligands replace the weak `H_(2)O` ligands forming `[CuCl_(4)]^(2-)` ion which has bright green colour.
`[Cu(H_(2)O)_(4)]^(2+)+4Cl^(-)rarrunderset("Tetrachloridocuprate(II)")[CuCl_(4)]^(2-)+4H_(2)O`