$a$ and $b$ are van der Waals constants for gases. Chlorine is more easily liquefied than ethane because

The pressure of a real gas is less than the pressure of an ideal gas because of .....

If the inversion temperature of a gas is $-80\,^{\circ}C$,then it will produce cooling under the Joule-Thomson effect at ............... $K$.

For real gases,the relation between $p$,$V$,and $T$ is given by the van der Waals equation:
$(p + \frac{an^2}{V^2})(V - nb) = nRT$
Where $a$ and $b$ are van der Waals constants,$nb$ is approximately equal to the total volume of the molecules of a gas,and $a$ is the measure of the magnitude of intermolecular attraction.
$(i)$ Arrange the following gases in the increasing order of $b$. Give reason: $O_2, CO_2, H_2, He$
$(ii)$ Arrange the following gases in the decreasing order of magnitude of $a$. Give reason: $CH_4, O_2, H_2$

At very low pressure,if the molar volume of $CO_2$ is constant,its compressibility factor is ..........

$A$ real gas would be most likely to obey the ideal gas laws at