The phase diagram for a pure substance is shown below. What is the lowest temperature at which liquid can exist?

Question

The phase diagram for a pure substance is shown below.  What is the lowest temperature at which liquid can exist?

Quizplus · Accepted Answer

The lowest temperature at which liquid can exist is the melting/freezing point, which corresponds to the line separating the solid and liquid phases. Following this line downwards, we see that it intersects the x-axis (pressure axis) at approximately 200 K. Therefore, the correct answer is C) 200 K. A) 400 K and E) 250 K correspond to the boiling/condensation point and are not relevant to this question. B) 0 K is the absolute zero point and not a temperature where any phase transitions can occur. D) 150 K is not on any of the phase boundary lines.

The Phase Diagram for a Pure Substance Is Shown Below