Question

The ratio on the pressure-temperature phase diagram where all the three phase co-exist is called:

• A. Sublimation point
• B. Fusion point
• C. Triple point
• D. Vaporisation point

Answer 1

The correct option is C Triple point

Key Idea steam line, ice and hoar - frost line meet at triple point
In the p -T diagram of water, if the three curves AB, CD and EF are extended, they came to meet at a point P, called the triple point
Therefore, triple point of a substance is a point in the phase diagram representing a particular set of pressure and temperature at which the solid, liquid and vapour phase of the substance can coexist.
For water, the values of pressure and temperature corresponding to triple point P are 0.46 cm of mercury and 273.16K (or ${0.01}^{o}C$) respectively.