The bleaching action of chlorine is permanent while that of sulphur dioxide is temporary. Why?

Explanation

To understand why the bleaching action of chlorine is permanent while that of sulfur dioxide is temporary, we can break down the processes involved in each case.

### Step 1: Understand the Bleaching Action of Chlorine
Chlorine (Cl2) acts as a bleaching agent primarily through oxidation. When chlorine is introduced to a moist environment, it reacts with water (H2O) to form hydrochloric acid (HCl) and hypochlorous acid (HClO). The hypochlorous acid is unstable and dissociates to release nascent oxygen (O), which is a powerful oxidizing agent.

**Reaction:**
\[ \text{Cl}_2 + \text{H}_2\text{O} \rightarrow \text{HCl} + \text{HClO} \]
\[ \text{HClO} \rightarrow \text{HCl} + \text{O} \]
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