The values of van der Waals' constant '$a$' for gases $O_2, N_2, NH_3$,and $CH_4$ are $1.360, 1.390, 4.170$,and $2.253 \ L^2 \ atm \ mol^{-2}$ respectively. The gas which can be most easily liquefied is

Positive deviation from ideal behaviour is due to the fact that

The compressibility factor $(Z)$ of a gas is less than unity at $STP$,then:

The Van der Waals parameters for gases $W$,$X$,$Y$,and $Z$ are given below. Which one of these gases has the highest critical temperature?

$Gas$	$a \ (atm \ L^2 \ mol^{-2})$	$b \ (L \ mol^{-1})$
$W$	$4.0$	$0.027$
$X$	$8.0$	$0.030$
$Y$	$6.0$	$0.032$
$Z$	$12.0$	$0.027$

For $1$ mol of a real gas kept at constant temperature $T$,the graph of $PV$ vs $P$ intersects the $PV$ axis at $20$. Hence,the temperature $T$ is ($R$ = universal gas constant).

At a given temperature $T$,gases $Ne$,$Ar$,$Xe$,and $Kr$ are found to deviate from ideal gas behaviour. Their equation of state is given as $P = \frac{RT}{V - b}$ at $T$. Here,$b$ is the van der Waals constant. Which gas will exhibit a steeper increase in the plot of $Z$ (compression factor) versus $P$?