At low pressure,the van der Waals equation becomes

$A$ gas at $350 \; K$ and $15 \; bar$ has a molar volume $20$ percent smaller than that for an ideal gas under the same conditions. The correct option about the gas and its compressibility factor $(Z)$ is

Match the Van der Waals constant $a$ (in $L^2 \cdot bar \cdot mol^{-2}$) for the following gases:

Gas	$a$ value
$1. C_6H_{6(g)}$	$a. 0.217$
$2. C_6H_5CH_{3(g)}$	$b. 5.464$
$3. Ne_{(g)}$	$c. 18.000$
$4. H_2O_{(g)}$	$d. 24.060$

The Vander Waals equation for $0.5 \ mol$ of a gas is:

At very high pressures,the compressibility factor of one mole of a gas is given by

The values of the 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. Which gas can be liquefied most easily?