Which orbital does not undergo degeneracy

The orbital that does not undergo degeneracy is the s-orbital.

• Degeneracy refers to orbitals having the same energy level.
• An s-orbital is spherical and there is only one s-orbital for each principal energy level (e.g., 1s, 2s, 3s). Since there are no other s-orbitals at the same energy level to share energy with, it is not degenerate.
• In contrast, p-orbitals (three degenerate orbitals: p_x, p_y, p_z), d-orbitals (five degenerate orbitals), and f-orbitals (seven degenerate orbitals) exist in sets that have the same energy in an isolated atom.

The final answer is $\text{s-orbital}$.