Find the typical de- Broglie wave length associated with a Helium gas at room temperature $(27^{\circ})$ and latm pressure, and compare it with the mean separation between two atoms under there conditions .

Question

$\begin{array}{1 1} \frac{\lambda}{r}=0.21 \\ \frac{\lambda}{r}=2.1 \\ \frac{\lambda}{r}=21 \\ \frac{\lambda}{r}=0.021 \end{array} $