How is the presence of `SO^(2)` detected?

Explanation

Sulphur dioxide `(SO_(2))` has a pungent odour and can be detected by the following tests:
1. `SO_(2)` turns orange acidified `K_(2)Cr_(2)O_(7)` solution green due to reduction of `CrO_(7)^(2-)` to `Cr^(3+)` ions.
`Cr_(2)O_(7)^(2-)+3SO_(2)+2H^(+)to2Cr^(3+)+3SO_(4)^(2-)+H_(2)O`
2. `SO_(2)` turns pink `KMnO_(4)` solution colourless due to reduction of `MnO_(4)^(-)` to `Mn^(2+)` ions
`2MnO_(4)^(-)+5SO_(2)+2H_(2)Oto2Mn^(2+)+5SO_(4)^(2-)+4H^(+)`