The atoms in gas ( gas constant R=8.31 J/mol K) can be treated as classical particles if their de Broglie wavelength L is much smaller than the average separation between the particles d. Consider monatomic helium gas (mHec^2 = 3727 MeV, molar mass 4g/mol) at 1.0 atmosphere of pressure (1.0×10^5) and the room temperature ( T = 293 K)

Question

The atoms in gas ( gas constant R=8.31 J/mol K) can be treated  as classical particles if their de Broglie wavelength    L  is much smaller than the average separation  between the particles d. Consider monatomic helium gas (mHec^2  = 3727 MeV, molar mass 4g/mol) at 1.0 atmosphere of pressure (1.0×10^5) and the room temperature ( T = 293 K)
a.	Estimate d for this gas ( d = ( # atoms/vol) ^-1/3)
b.	Find the average de Broglie wavelength L of the atoms in the gas ( KE = ( 3/2) KB T,  KB = 8.617 * 10 –E5 eV/K)
c.	Find the pressure that would make d equal to L from b
d.	Find the temperature that would make the average L equal to d from part a

I posted afew hour and saw the answer , I thank you so much, but I don’t understand why V helium is still 22,4 L at 1.0 atm, and 293 K)
Can we use the equation h/sq of 2mKE  to find the average L?