Pure `H_2O_2` is

Options

A. semi-solid
B. liquid
C. solid
D. gas

Answer

To determine the physical state of pure hydrogen peroxide (H₂O₂), we can analyze the properties of the substance based on its characteristics and behavior.

### Step-by-Step Solution:

1. **Understanding the Chemical Composition**:
- Hydrogen peroxide (H₂O₂) consists of two hydrogen atoms and two oxygen atoms. This composition is crucial in determining its physical state.

2. **Physical State of H₂O₂**:
- At room temperature, pure hydrogen peroxide is known to be a thick, syrupy liquid. This indicates that it does not exist as a solid or gas under normal conditions.

3. **Analyzing the Options**:
- **Option A: Semi-solid** - This does not accurately describe pure H₂O₂, as it is not in a semi-solid state.
- **Option B: Liquid** - This aligns with the known properties of pure hydrogen peroxide, which is a liquid at room temperature.
- **Option C: Solid** - Pure H₂O₂ does not exist as a solid under normal conditions.
- **Option D: Gas** - Hydrogen peroxide is not a gas at room temperature.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Option B: Liquid**. Pure hydrogen peroxide is a thick, syrupy liquid.

### Final Answer:
**Pure H₂O₂ is a liquid (Option B).**