The critical temperatures $(T_C)$ of some gases are given below:

Gases	$H_2, He, O_2$
$T_C \ (K)$	$33.2, 5.3, 154.3$

Based on the above data,what is the order of liquefaction of these gases? Start writing the order from the gas that liquefies first.

$A$ liquid can exist only,

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.

However great the pressure,a gas cannot be liquefied above its

What is the Andrews isotherm graph used for?

The isotherms of a gas are shown below:
Among the following:
$(i)$ At $T_1$,the gas cannot be liquefied.
$(ii)$ At point $B$,liquid starts to appear at $T_2$.
$(iii)$ $T_c$ is the highest temperature at which the gas can be liquefied.
$(iv)$ At point $A$,a small increase in pressure condenses the whole system to a liquid.
The correct statements are: