At which of the following conditions can a gas be liquefied? ($T_c$ and $P_c$ are critical temperature and pressure.)

Assertion : Gases do not liquefy above their critical temperature,even on applying high pressure.
Reason : Above critical temperature,the molecular speed is high and intermolecular attractions cannot hold the molecules together because they escape because of high speed.

Gases possess characteristic critical temperature which depends upon the magnitude of intermolecular forces between the particles. Following are the critical temperatures of some gases:

$Gases$	$Critical \ temperature \ in \ Kelvin$
$P$	$33.2$
$Q$	$5.3$
$R$	$154.3$
$S$	$126$

From the above data,what would be the order of liquefaction of these gases? Start writing the order from the gas liquefying first.

What is meant by the vapor of a substance like $CO_2$?

Identify the incorrect statement regarding the properties of liquids and vapors.

Two different gases $A$ and $B$ are filled in separate containers of equal capacity under the same conditions of temperature and pressure. On increasing the pressure slightly,gas $A$ liquefies,but gas $B$ does not liquefy even on applying high pressure until it is cooled. Explain this phenomenon.