Air can oxidize sodium sulphite in eq. solution but cannot do so in the case of sodium arsenite. If however, air is passed through a solution containing both sodium sulphite & sodium arsenite then both are oxidized. This is an example of :-

Options

A. Positive catalysis
B. Negative catalysis
C. Induced catalysis
D. Auto catalysis

Answer

To solve the question, we need to analyze the behavior of sodium sulfite and sodium arsenite when exposed to air (oxygen) in an aqueous solution.

### Step-by-Step Solution:

1. **Understanding the Reactivity of Sodium Sulfite and Sodium Arsenite**:
- Sodium sulfite (Na2SO3) can be oxidized by air (oxygen) in an aqueous solution. This means that when air is bubbled through a solution of sodium sulfite, it reacts with oxygen to form sodium sulfate (Na2SO4).
- Sodium arsenite (Na3AsO3), on the other hand, does not get oxidized by air alone. This indicates that sodium arsenite is less reactive towards oxidation compared to sodium sulfite.

2. **Observation in Mixed Solution**:
- When both sodium sulfite and sodium arsenite are present in the same solution and air is passed through it, both compounds are oxidized. This suggests that the presence of sodium sulfite somehow facilitates the oxidation of sodium arsenite.

3. **Concept of Induced Catalysis**:
- The phenomenon observed here is known as **induced catalysis**. In this case, the oxidation of sodium sulfite acts as a catalyst that induces the oxidation of sodium arsenite.
- An induced catalyst is a substance that increases the rate of a reaction without being consumed in the process and can enhance the reactivity of another substance.

4. **Conclusion**:
- Therefore, the situation described in the question is an example of **induced catalysis**, where the oxidation of sodium sulfite induces the oxidation of sodium arsenite when both are present in the solution.

### Final Answer:
This is an example of **induced catalysis**.

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