Which of the following statement(s) is/are correct?
A. `S_(2)O_(8)^(2-)` oxidises `Mn^(2+)` to give pink colour.
B. `MnO_(4)^(2-)` disproportionates to yield `MnO_(4)^(-)` and `MnO_(2)` in presence of `H^(+)` ions.
C. In `Cr_(2)O_(7)^(2-)` each Cr is linked to four oxygen atoms.
D. `Ti^(3+)` is purple while `Ti^(4+)` is colourless.
