SDSU Chemistry Placement Test 2025 – 400 Free Practice Questions to Pass the Exam

The term that describes the point at which a gas can no longer be compressed into a liquid is known as the critical point. At this specific temperature and pressure, the properties of the gas and liquid phase become indistinguishable from each other. This means that no matter how much pressure is applied, the gas cannot be transformed into a liquid.

This phenomenon occurs because, at the critical point, the density of the gas and the liquid become equal. Beyond this point, the distinction between the gaseous and liquid states disappears, resulting in a supercritical fluid, which can diffuse through solids like a gas and dissolve substances like a liquid.

The other terms mentioned—freezing point, boiling point, and melting point—refer to different phase transitions, such as the transition from solid to liquid, or from liquid to vapor, under specific conditions, and do not define a limit on the compressibility of a gas into a liquid. Thus, the critical point uniquely represents the extreme condition at which the shift from gaseous to liquid state ceases to be feasible.