5.C.: Nodes of the hydrogen atom eigenstates
Radial nodes occur when the wave function for the electron is zero on a spherical surface of a particular radius (... hence the name radial node). Shown on the right is a plot of the probability of the 3s wave function. The two radial nodal surfaces are indicated in the figure.
Angular nodes occur when the wave function for the electron is zero along along directions specified by a particular angle (...hence the name angular node). Shown on the left is a plot of the probability of the 2p wave function. The angular nodal surface indicated in the figure is a plane that makes a 90° angle with the z-axis
In the hydrogen atom, 
where C = 2.18 * 10 -18 J.