# Why can two s orbitals NOT be degenerate?

Degenerate means that they have the same energy. $n s$ orbitals cannot be degenerate with respect to themselves because there is only one $n s$ orbital for a given $n$.
For instance, the one $5 s$ and five $4 d$ orbitals in yttrium ($\text{Y}$) may as well be considered degenerate with respect to each other, as their orbital potential energies are about $- \text{6.70 eV}$ and $- \text{6.49 eV}$, respectively (Appendix B.9), a difference of $\text{0.39 eV}$, or ${\text{8.99 kcal/mol e}}^{-}$ (3.82% the $1 s \to 2 s$ transition energy of the hydrogen atom).