P=1 atm,T=300 K
use PV=RT(For 1 mole of the gas)
V=(RT)/P
V=(0.0821*300)/1
V=24.63 litres
1 mole of an ideal gas occupies 24.63 litres at 300 K
i.e.6.023*(10^23)molecules occupy 24.63 litres
1 molecule occupies 'x' litres
x=(1*24.63)/[6.023*(10^23)]
x=4.0893*[10^(-23)]litres
1 molecule occupies 4.0893*[10^(-23)]litres