(b) Draw a one-component phase diagram (pressure-temperature) and use phase rule to rationalize your diagram. [Hint: Why "point", "line" or "area" in the diagram] (10%)

4. Draw a two-component, temperature-composition, solid-liquid diagram for a system where compound of formula AB2 forms that melts incongruently, and there is a negligible solid-solid solubility. Label the regions of the diagrams, stating what materials are present and whether they are solid or liquid. (15 %)