Question

Under which of the following conditions, the gas can be liquified?
A.Above its critical temperature
B.At its critical temperature
C.Below its critical temperature
D.At any temperature

Answer 1

From the application of high pressure in a closed container, any gas can be liquified. Liquification of gases can also be called condensation which is the physical process of conversion of a gaseous state into a liquid state. This liquification of gas needs high pressure and low temperature which is achieved by using compressions and expansions. This can be done with turbo expanders.

Complete step by step answer:
The critical temperature can be defined as the temperature in which a gas has the capacity to hold all the molecules within it. When we increase the temperature to a certain range then it decreases and finally a condition comes when it breaks.
Conditions for liquefaction of gas:
a. High temperature and high pressure.
b. Low temperature and high pressure.
c. Low temperature and low pressure.
d. High temperature and low pressure.
The liquefaction of a gas depends on the molecular forces between the molecules. When the temperature is increased, the molecular forces decrease. So, the temperature. Therefore, there is temperature under which a gas can be liquified which is known as critical temperature. The critical temperature is denoted by ${T_c}$. So, the gas can be liquified under the given conditions of temperature and pressure –
When the temperature is less than the critical temperature and the pressure is more than critical pressure then, the gas can be liquified.
$T < {T_c}{\text{ }}and\;P > {P_c}$

So, the correct answer is Option B.

Note:
The real gas particles have volume, so, the gases liquefy when their component molecules inherit, contact and interact with one another. But a perfect gas has particles with zero volume, and no intermolecular interactions. Therefore, it cannot liquefy.