Pick out the incorrect statement regarding `H_2O_2`.

Options

A. `H_2O_2` is kept in waxlined bottle
B. `H_2O_2` acts both as oxidizing and reducing agent
C. It is not possible to determine its boiling point at atmospheric pressure
D. `H_2O_2` does not react with acidified `KMnO_4`

Answer

To solve the question "Pick out the incorrect statement regarding H₂O₂," we will analyze each of the provided statements about hydrogen peroxide (H₂O₂) to determine which one is incorrect.

### Step-by-Step Solution:

1. **Statement 1: Hydrogen peroxide is kept in waxed line bottles.**
- **Analysis:** Hydrogen peroxide is indeed very reactive and decomposes in the presence of light. To prevent this decomposition, it is stored in dark or waxed line bottles that block light. This statement is correct.

2. **Statement 2: Hydrogen peroxide acts both as an oxidizing and reducing agent.**
- **Analysis:** Hydrogen peroxide can act as an oxidizing agent in acidic conditions and as a reducing agent in basic conditions. This dual behavior is well-documented in chemistry. Therefore, this statement is also correct.

3. **Statement 3: It is not possible to determine the boiling point at atmospheric pressure.**
- **Analysis:** This statement is misleading. While hydrogen peroxide does decompose upon heating, it is still possible to determine its boiling point under controlled conditions. The boiling point of H₂O₂ is known to be around 151.2 °C (424.4 K) at atmospheric pressure. Thus, this statement is incorrect.

4. **Statement 4: Hydrogen peroxide does not react with acidified KMnO₄.**
- **Analysis:** This statement is incorrect. Hydrogen peroxide does react with acidified potassium permanganate (KMnO₄), reducing it and causing a color change from purple to colorless as the MnO₄⁻ ion is reduced to Mn²⁺. Therefore, this statement is also incorrect.

### Conclusion:
The incorrect statement regarding H₂O₂ is **Statement 3: It is not possible to determine the boiling point at atmospheric pressure.**