Which is an example of auto-catalysis?

Options

A. Hydrolysis of methyl acetate
B. Oxidation of `Na_(2)SO_(3)` in presence of `Na_(2)AsO_(3)`
C. Oxidation of oxalic acid by `KMnO_(4)`
D. None of these

Answer

To solve the question regarding examples of autocatalysis, we need to understand what autocatalysis is and analyze the given options accordingly.

### Step-by-Step Solution:

1. **Understanding Autocatalysis**:
- Autocatalysis is a type of catalysis where one of the products of the reaction acts as a catalyst for the reaction itself. This means that as the reaction proceeds, the formation of the product accelerates the reaction rate.

2. **Analyzing Option A: Hydrolysis of Methyl Acetate**:
- The reaction involves the hydrolysis of methyl acetate (CH3COOCH3) in the presence of dilute HCl, producing acetic acid (CH3COOH) and methanol (CH3OH).
- In this reaction, acetic acid (the product) can act as a catalyst for the hydrolysis process. Therefore, this is an example of autocatalysis.

3. **Analyzing Option B: Oxidation of Na2SO3 in Presence of Na2AsO3**:
- In this case, sodium sulfite (Na2SO3) and sodium arsenate (Na2AsO3) are mixed, and upon exposure to air, both get oxidized.
- Here, the presence of one compound influences the oxidation of the other, but no product acts as a catalyst for the reaction. This is an example of induced catalysis, not autocatalysis.

4. **Analyzing Option C: Oxidation of Oxalic Acid by KMnO4**:
- In this reaction, oxalic acid (C2O4^2-) is oxidized by potassium permanganate (KMnO4), resulting in the formation of Mn2+ ions.
- The Mn2+ ions produced in the reaction can catalyze the oxidation of oxalic acid, making this an example of autocatalysis.

5. **Conclusion**:
- Based on the analysis, both Option A (hydrolysis of methyl acetate) and Option C (oxidation of oxalic acid by KMnO4) are examples of autocatalysis.
- Thus, the correct answer is **Option A and Option C**.

### Final Answer:
**Option A and Option C are correct examples of autocatalysis.**

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