Hydrogen atom has only one electron, so mutual repulsion between electrons is absent. However, in multielectron atoms mutual repulsion between the electrons is significant. How does this affect the energy of an electron in the orbitals of the same principal quantum number in multielectron atoms ?

Explanation

The energy of an electron in a multielectron atom depends on principal quantum number and angular quantum number
Reason - 1 : in multieletron atom the attraction addition and nucleus is present act in addition do that repulsion between electron electron is also there
Reason - 2 : Out most electron are protected by change . As the shielding effect increasing teh nucleus charge decrease so the distance of electron is more .
Both the attractly and repulsive interactin depends upon the shell and shape of orbital in which the electron is present.
The capacity of screening is respectively decrease in s,p, d So thir energy `3s lt 3p lt 3d`