In van der Waals equation of state,the constant $b$ is a measure of

The van der Waals equation is valid for $......$.

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

The relation between pressure exerted by an ideal gas $(P_{ideal})$ and observed pressure $(P_{real})$ is given by the equation
$P_{ideal} = P_{real} + \frac{an^2}{V^2}$
$(i)$ If pressure is taken in $N \ m^{-2}$,number of moles in $mol$,and volume in $m^3$,calculate the unit of $a$.
$(ii)$ What will be the unit of $a$ when pressure is in atmosphere and volume in $dm^3$?

What are the corrections made to the pressure and volume of real gases compared to ideal gases?

Give the difference between an Ideal Gas and a Real Gas.