Answer:
All the three phases coexist at triple point.
Explanation:
The triple point of water is 0.01°C (273.16K) and 4.58 mmHg. At this temperature and pressure the water exist in all the three forms or phases.
The three phases are solid, liquid and gas.
It is like water is boiling and freezing at the same time.
If we change temperature or pressure, even slightly, one of the phases of water will disappear (based on changes made).
