A particular point on a line of a phase diagram represents:
C. The melting point or boiling point of a substance at a specific pressure.
Here's a detailed explanation:
Phase diagrams are graphical representations that show the conditions of temperature and pressure under which a substance exists in different phases (solid, liquid, gas). The lines on the phase diagram are called phase boundaries and they separate different phases from one another.
Each point on these lines (or phase boundaries) indicates the specific temperature and pressure at which two phases coexist in equilibrium. For examples:
- A point on the line between the solid and liquid regions indicates the melting point of the substance at a specific pressure, where the substance transitions between solid and liquid states.
- A point on the line between the liquid and gas regions indicates the boiling point of the substance at a specific pressure, where the substance transitions between liquid and gas states.
- A point on the line between the solid and gas regions indicates the sublimation point of the substance at a specific pressure, where the substance transitions directly from solid to gas.
Each of these points of equilibrium signifies the precise conditions (temperature and pressure) at which the phase change occurs. Therefore, the correct interpretation of a point on a line in a phase diagram is indeed the melting point or boiling point of a substance at a given pressure.
