For which of the following gases is the value of the van der Waals constant $'a'$ expected to be the highest?

For a real gas (molar mass $= 60 \, g/mol$),if the density at the critical point is $0.80 \, g/cm^3$ and its critical temperature $T_c = \frac{4 \times 10^5}{821} \, K$,then the van der Waals constant $a$ (in $atm \, L^2 \, mol^{-2}$) is:

The following data is obtained for one mole of a gas. The gas deviates from ideal behavior in the pressure (in bar) range:

$P \text{ (bar)}$	$\frac{PV}{RT}$
$1$	$1$
$2$	$1$
$3$	$1$
$3.1$	$1.2$
$3.5$	$1.4$
$4.0$	$1.5$

Explain the conditions under which a real gas exhibits ideal gas behaviour.

What is the compressibility factor $(Z)$ for the deviation of real gases from ideal behavior?

For a gas,deviation from ideal behaviour is maximum at