The wave function (Ψ) of 2s is given by
Ψ2s=122π(1a0)1/2(2-ra0)e-r/2a0
At r=r0, radial node is formed. Thus, r0 in terms of a0. [2023]
(2)
At node Ψ2s2=0, Ψ2s=0
So, (2-ra0)=0
2-r0a0=0 ⇒ r0=2a0