Estimate the boiling point of seawater there, assuming it was pure. Clausius-Clapeyron can be rearranged to tell us what T will boil water at such enormous pressures knowing that 373 K suffices at 1 atm. That has two effects. First, seawater is slightly more dense than pure water since it s holding the weight of that salt. I m willing to bet that the extra pressure due to the increased density will change T more than does the boiling point elevation colligative property, but let s see.
Density is the ratio of mass to volume.
Rationalize the progression down the Periodic Table of the physical states of the dihalogens at standard conditions in terms of their intermolecular forces. So the dihalogens must hold themselves together in condensed phases via the weak London forces. That means that they are less strongly held as reflected in the decrease in electronegativity in the dihalogens going down the table. Use freezing point depression to explain why a mixture of two compounds has a melting range while either compound alone has a melting point. No liquid can be found above the critical point.