It is possible to liquefy a gas

Options

A. at a temperature above critical temperature and at a pressure above critical pressure
B. at a temperature at critical temperature and at a pressure lower than critical pressure
C. at critical temperature and a pressure equal to critical pressure
D. at a temperature above critical temperature and pressure below critical pressure.

Answer

C

Explanation

Liquefaction of gases takes place at a temperature either equal to critical temperature or at a temperature lower than critical temperature. Also at the critical temperature, the pressure would be equal to critical pressure.