According to the phase diagram given, which of the following is INCORRECT?

◦ At the temperature and pressure of point 1, substance U exists as a three-phase equilibrium system.
◦ At the temperature and pressure of point 2, substance U exists as a one-phase gaseous system.
◦ At the temperature and pressure of point 3, substance U exists as a two-phase system.
◦ If the U(s)

U(l) system is maintained at the temperature of point 4 while pressure is decreased steadily to about 300 Torr, more U will freeze.
◦ There are no conditions of temperature and pressure under which solid U will vaporize without melting first.