The dashed box labels the region beyond point C.
The shaded region beyond C represents:
- A
Pure solid phase
- Bcheck_circle
A supercritical fluid with no distinct liquid/gas phases
- C
A metastable vapor
- D
An ideal gas
Explanation
Beyond the critical point both temperature and pressure exceed Tc and Pc, producing a supercritical fluid in which the liquid-gas phase boundary disappears.