At $S.T.P.$,if the compressibility factor $(Z)$ of a gas is less than $1$,then which of the following is true?

$1 \ mol$ of a real gas is kept at a high pressure of $100 \ bar$ at $300 \ K$. If the van der Waals constant $b$ is $0.005 \ L \ mol^{-1}$, what are the values of the compressibility factor $Z$ of the gas and the $\%$ deviation of volume from ideality?

$Z$	$\%$ Deviation

For real gases,the relation between $P$,$V$ and $T$ is given by the van der Waals equation,$(P + \frac{an^2}{V^2})(V - nb) = nRT$. For the following gases $CH_4, CO_2, O_2, H_2$,which gas will have $(i)$ highest value of $'a'$ $(ii)$ lowest value of $'b'$?

If $Z$ is a compressibility factor,the van der Waals equation at low pressure can be written as:

The compressibility factor $(Z)$ of a gas at moderate pressure is:

Define the compressibility factor $(Z)$ in terms of the molar volume of a gas.