Given that the pressure in a phase diagram remains constant, what type/s of phase changes can occur as temperature is increased?

Use Trouton's rule to estimate the enthalpy of vaporization for a substance whose boiling point is 80 C.

Region x is (liquid, Supercritical Fluid, Solid, Gas) Region w is (liquid, Supercritical Fluid, Solid, Gas) Region y is (liquid, Supercritical Fluid, Solid, Gas) Point z is (liquid, Supercritical Fluid, Solid, Gas)

Use the References to access important values if needed for this question. The normal boiling point of liquid pentane is 309 K. Assuming that its molar heat of vaporization is constant at 26.8 kJ/mol, the boiling point of C5H12 when the external pressure is 1.23 atm is K.

Glaciers are not stationary bodies of ice, but instead slowly move over time (mean speed of 1 meter/day). One reason for this is because these very large glaciers melt from the bottom, and the liquid water beneath the glacier acts as a lubricant for the glacier to move.    Using the phase diagram for water (below) and concepts discussed in class, what is one potential reason that glaciers melt from the bottom at temperatures below 0°C?