Sodium sulphite `(Na_(2)SO_(3))` is added to meat as a preservative. The presence of `Na_(2)SO_(3)` can be detected by adding dil. `H_(2)SO_(4)` when the pungent smelling gas evolved turns the lime water milky. The gas evolved was detected as sulphur dioxide. The `SO_(2) " to "SO_(4)^(2-)` in titration.
`SO_(2)+2H_(2)O+I_(2) to 4H^(+)+SO_(4)^(2-)+2I^(-)`
In order to check the results of titration, excess barium chloride is added to the final solution. The resulting precipitate is collected and weighed.
Q. `SO_(2)` gas is used as bleaching agent. Its bleaching action is :

Options

A. temporary and due to its oxidizing nature
B. temporary and due to its reducing action
C. permanent and due to its oxidizing nature
D. permanent and due to its reducing action

Answer

To understand the bleaching action of sulfur dioxide (SO₂), we can break down the process step by step.

### Step 1: Understanding the Nature of SO₂
Sulfur dioxide is a colorless gas with a pungent odor. It is known for its ability to act as a bleaching agent.

**Hint:** Consider the chemical properties of SO₂ and how they relate to its function as a bleaching agent.

### Step 2: Reaction of SO₂ with Water
When sulfur dioxide dissolves in water, it forms sulfurous acid (H₂SO₃), which can further oxidize to sulfuric acid (H₂SO₄). During this process, nascent hydrogen is produced.

**Hint:** Recall the reactions of SO₂ in aqueous solutions and the formation of acids.

### Step 3: Role of Nascent Hydrogen
The nascent hydrogen produced from the reaction of SO₂ with water acts as a reducing agent. Reducing agents are substances that can donate electrons to other substances, leading to a reduction in oxidation state.

**Hint:** Think about the definition of reducing agents and their role in chemical reactions.

### Step 4: Bleaching Action
The bleaching action of SO₂ is due to this reducing property. When it reduces colored compounds, it effectively removes their color, resulting in a bleaching effect.

**Hint:** Consider how the reduction of colored compounds leads to a loss of color.

### Step 5: Temporary Nature of Bleaching
The bleaching effect of SO₂ is temporary. This is because, upon exposure to atmospheric oxygen, the bleached materials can be oxidized back to their original colored state. Thus, the color can be restored after the bleaching process.

**Hint:** Reflect on the reversibility of the bleaching process and the role of oxygen in restoring color.

### Conclusion
Based on the above steps, we conclude that the bleaching action of sulfur dioxide is temporary and due to its reducing action.

**Final Answer:** The correct option is: **temporarily and due to its reducing action.**

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