According to Avogadro law the volume and moles of a gas is directly proportional at constant pressure and temperature.
Number of moles is therefore number of molecules/Avogadro constant(6.02 x10^23)
(2.2 x10^24)/(6.02 x10^23) =3.654moles
Every moles of an ideal gas occupy 22.4L at S.T.P
therefore volume is
3.654 x22.4L=81.85L
