Bleaching of flowers by chlorine is permanet, while that by sulphur dioxide is tempory. Explain.

Answer

`Cl_(2)` bleaches coloured material by oxidation :`Cl_(2)+H_(2)Oto2HCl +[O]`
Coloured material +`[O]to` Colourless
and hence bleaching is permanent.
On the other hand, `SO_(2)` bleaches coloured material by reduction and hence bleaching is temporary since when the bleached colourless material is exposed to air, it gets oxidized and the colour is restored.
`SO_(2)+2H_(2)Oto2H_(2)SO_(4)+2[H]`
Coloured material +`[H]to` Colourless material `underset("oxidation")overset("Aerial")to` Coloured material.