What is special about this part of the curve (what is physically happening to the system at this point)?

Consider the following phase diagram to answer the questions. Be VERY complete in your answers, write neatly, and show all your work. Pressure Temperature a) Label on the plot the “triple point”. What is special about this part of the curve (what is physically happening to the system at this point)? b) Label the areas on the plot that correspond to the liquid, vapor, and solid phases, and shade in the area that corresponds to a supercritical fluid. c) Label the critical temperature and critical pressure. d) Label the melting point (Tmelt) of the substance at pressure Pi on the phase diagram. e) Label the boiling point (Tbp) of the substance at pressure P2 on the phase diagram.