The phase diagram of a pure substance is shown below. If a sample of this substance at 1 atm is heated from 0 C (point M) to 30.0 C and the pressure is then decreased to 0.3 atm, what phase will the substance be in? Pressure (atm) 1.5- 1.0- 0.5 solid -10 0 10 20 30 40 50 Temperature (C) M gas liquid critical point supercritical fluid