Which of the following reactions is an example of auto catalysis ?

Options

A. `2AsH_(3(s))rarr2AS_((s))+3H_(2(g))`
B. `N_(2(g))+3H_(2(g))overset(Fe(s))(rarr)2NH_(3(g))`
C. `2SO_(2(g))+O_(2(g))overset(NO(g))(rarr)2SO_(3(g))`
D. `C_(12)H_(22)O_(11)+H_(2)O_((1))overset(H^(+)(1))(rarr)C_(6)H_(12)O_(6(i))+C_(6)H_(12)O_(6(i))`

Answer

To determine which of the given reactions is an example of autocatalysis, we first need to understand what autocatalysis is. Autocatalysis occurs when one of the products of a reaction acts as a catalyst for that same reaction.

Let's analyze each option step by step:

### Step 1: Analyze Option A
**Reaction:** \(2AsS_3 \rightarrow 2As + 3S_2\)

- In this reaction, there is no catalyst involved. The products are arsenic (As) and sulfur (S), but neither acts as a catalyst for the reaction.
- **Conclusion:** This is not an example of autocatalysis.

### Step 2: Analyze Option B
**Reaction:** \(N_2 + 3H_2 \rightarrow 2NH_3\)

- This reaction uses iron as a catalyst. A catalyst is added externally and is not a product of the reaction.
- **Conclusion:** This is not an example of autocatalysis.

### Step 3: Analyze Option C
**Reaction:** \(2SO_2 + O_2 \rightarrow 2SO_3\)

- This reaction uses nitrogen monoxide (NO) as a catalyst. Again, this is an external catalyst and not a product of the reaction.
- **Conclusion:** This is not an example of autocatalysis.

### Step 4: Analyze Option D
**Reaction:** \(C_{12}H_{22}O_{11} + H_2O \rightarrow C_6H_{12}O_6 + C_6H_{12}O_6\)

- In this reaction, HBr is added as a catalyst. The catalyst is not produced in the reaction.
- **Conclusion:** This is not an example of autocatalysis.

### Step 5: Identify the Correct Option
After analyzing all the options, we find that none of the reactions listed in options A, B, C, or D demonstrate autocatalysis.

However, if we consider the context of the question and the video transcript, it seems that the correct answer is implied to be option E, which is not explicitly listed in the options provided.

### Final Conclusion
The reaction that demonstrates autocatalysis is when one of the products acts as a catalyst for the same reaction. Based on the analysis, none of the provided options clearly represent autocatalysis, but the video suggests that option E (not listed) would be the correct choice.