Question

What is the action of $C{l_2}$ on $S{O_2}$

Answer 1

Bleach works by releasing oxygen molecules via an oxidation mechanism. Bleach releases oxygen molecules, which serve chromophore chemical bonds. The chromophore molecules that have changed either show no colour or a colour that is not visible in the visible spectrum. Our eyes perceive this lack of colour as white.

Complete answer: Chlorine's bleaching activity is irreversible since it requires the oxidation phase. Chlorine produces nascent oxygen as it reacts with water. This oxygen reacts with the pigments in the material, rendering it colourless. It has a strong oxidising effect. As a result, Chlorine's bleaching activity is irreversible. In this case, the reaction is as follows:
$C{l_2}{\text{ }} + {\text{ }}{H_2}O{\text{ }} \to {\text{ }}HCl{\text{ }} + {\text{ }}HClO$
Hypochlorous acid is a highly unstable substance that readily dissociates into nascent oxygen.
$HClO \to {\text{ }}HCl{\text{ }} + {\text{ }}\left[ O \right]$
$Colour{\text{ }}material + {\text{ }}\left[ O \right] \to Colourless$
Since it requires a reduction phase, sulphur di oxide's bleaching activity is only temporary. Sulphur dioxide depletes the oxygen in the coloured material, rendering it colourless. Atmospheric oxygen gradually replaces the removed oxygen, allowing the substance to recover its colour.
In this case, the reaction is as follows:
S{O_2} + 2{H_2}O \to {H_2}S{O_4} + 2[H]{\text{ }}\left( {nascent} \right)$$$$Colour{\text{ }}material + \left[ H \right] \to Colourless\;Colour{\text{ }}\left( {in{\text{ }}presence{\text{ }}of{\text{ }}air} \right)
Hence, overall we can conclude that Sulphur dioxide and chlorine are also effective bleaching agents. Chlorine's bleaching action is based on oxidation, whereas sulphur is based on reduction.
Chlorine produces nascent oxygen as it reacts with water. As oxygen reacts with a coloured material, it turns it colourless.
Sulphur dioxide depletes the oxygen content of the coloured material, rendering it colourless. However, ambient oxygen gradually replaces the extracted oxygen, allowing the substance to recover its colour.

Note:
Since it does not contain nascent oxygen, dry chlorine does not act as a bleaching agent. To solve this problem, it is a potent oxidising agent. It has a strong proclivity for ripping electrons from color-producing molecules and forming stable $C{l^ - }$ . The most sensitive molecules to oxidation are those that produce colour.