The Schrodinger wave equation for the 2s electron of a hydrogen atom is,
`psi_(2s)=(1)/(4sqrt(2pi))[(1)/(a_(0))]^(3//2)xx[2-(r)/(a_(0))]xxe^(-r//2a_(0))`
There is a radial node at the point, where `r=r_(0)` find the relation between `r_(0) and a_(0)`.

Explanation

The possibility of finding a 2s electron is,
`phi_(2s)^(2)=[(1)/(4sqrt(2pi))((1)/(a_(0)))^(3//2)xx(2-(r)/(a_(0)))xxe^(-r//2a_(0))]^(2)`
Node is defined as the point where probability of finding an electron is zero.
`therefore` If `r=r_(0),psi_(2s)^(2)=0" "therefore (1)/(32pi)((1)/(a_(0)))^(2)(2-(r_(0))/(a_(0)))^(2)e^(-r_(0)//2a_(0))=0`
The only factor that can be zero in the above expression is `(2-(r_(0))/(a_(0)))" "therefore 2-(r_(0))/(a_(0))=0," "or," "r_(0)=2a_(0)`.