Question

A gas can be liquefied at temperature $T$ and pressure $P$ provided

• A. $T = T_c$ and $P < P_c$
• B. $T < T_c$ and $P > P_c$
• C. $T > T_c$ and $P > P_c$
• D. $T > T_c$ and $P < P_c$

Answer 1

Answer: (B)

$T < T_c$ and $P > P_c$

Answer 2

A gas can be liquefied at temperature $T$ when it is lower than critical temperature, $T_{c}$ and pressure $p$ is greater than critical pressure.
Hence, $T< T_{c}$ and $p >p_{c}$.