The $Van \text{ der } Waals$ equation explains the behaviour of

Explain the compressibility factor $(Z)$.

The compressibility factor for a van der Waal gas at high pressure is

$A$ gas deviates from ideal behaviour at a high pressure because its molecules

Pressure versus volume graph for a real gas and an ideal gas are shown in the figure. Answer the following questions on the basis of this graph:
$(i)$ Interpret the behaviour of real gas with respect to ideal gas at low pressure.
$(ii)$ Interpret the behaviour of real gas with respect to ideal gas at high pressure.
$(iii)$ Mark the pressure and volume by drawing a line at the point where real gas behaves as an ideal gas.

The compressibility factor $(Z)$ of one mole of a van der Waals' gas of negligible '$a$' value is