Molar volume is the volume occupied by $1mol$ of any (ideal) gas at standard temperature and pressure $\left(\text{STP : 1 atmospheric pressure,}{0}^{\circ }C\right).$ Show that it is $22.4litres.$

Here, $R=8.31Jmo{l}^{-1}{K}^{-1}$

$T=0^{\circ }C=273K;n=1mole$

$P=1atm=0.76m$ of Hg column
$=0.76\times 13.6\times {10}^3\times 9.8=1.013\times {10}^{5}N/m^2$

To prove $V=22.4litre$

Using ideal gas equation $PV=nRT$,

$V=\frac{nRT}{P}$

$V=\frac{1\times 8.31\times 273}{1.013\times {10}^5}=22.4\times {10}^{-3}{m}^3$

$V=22.4litres$.