The point where all the three state (solid, liquid, vapour) of `H_2O` exist is known as

Options

A. Single point
B. Double point
C. Triple point
D. Solid point

Answer

To solve the question regarding the point where all three states (solid, liquid, and vapor) of H2O exist, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the States of Matter**:
- Water can exist in three states: solid (ice), liquid (water), and vapor (steam).

2. **Identifying the Unique Point**:
- There is a specific condition of temperature and pressure where all three states can coexist in equilibrium. This condition is known as the "triple point."

3. **Defining the Triple Point**:
- The triple point is defined as the unique set of conditions at which all three phases of a substance can coexist. For water, this occurs at a specific temperature and pressure.

4. **Finding the Values for Water**:
- For water (H2O), the triple point occurs at:
- Temperature: 273.16 K (or 0.01 °C)
- Pressure: 4.58 mm Hg

5. **Conclusion**:
- Therefore, the point where all three states of H2O exist is known as the "triple point."

### Final Answer:
The point where all three states (solid, liquid, and vapor) of H2O exist is known as the **triple point**.

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