Answer the following questions based on the P-T phase diagram of `CO_(2)`:
Describe qualitatively the changes in a given mass of solid `CO_(2)` at 10 atm pressure and temperature `- 65 ^(@) C` as it is heated up to room temperature at constant pressure.

Explanation

It turns to liquid phase and then to vapour phase. The fusion and boiling points are where the horizontal line on P-T diagram at the constant pressure of 10 atm intersects the fusion and vaporisation curves.