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 prinicipal quantum number in multielectron atoms?

Explanation

In hydrogen atom, the energy of an electron is determined by the value of n and in multielectron atom, it is determined by n+l . Hence for a given principal quantum. Number electrosn of s,p,d and f-orbtials have different energy (for s,p,d and f,l=01,2 and 3 respectively).