In a mole of water vapour at $STP$,the volume actually occupied or taken by the molecules (i.e.,Avogadro's No. $\times$ Volume of one molecule) is

At relatively high pressure,the van der Waals equation reduces to

The pressure $(p)$ and volume $(V)$ isotherm of a van der Waals' gas,at the temperature at which it undergoes gas to liquid transition,is correctly represented by

At $300 \ K$,one mole of a gas present in a $10 \ L$ flask exerted a pressure of $2.706 \ atm$. What is its compressibility factor $(Z)$? (Given $R=0.082 \ L \ atm \ mol^{-1} \ K^{-1}$).

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.

Dominance of strong repulsive forces among the molecules of the gas ($Z =$ compressibility factor)