Which element has the same number of energy levels as oxygen?

Elements have the same number of energy levels as oxygen.

Elements and definitions

Lithium - Lithium compounds, also known as lithium salts, are primarily used as a psychiatric medication. It is primarily used to treat bipolar disorder and treat a major depressive disorder that does not improve following the use of antidepressants.

Beryllium - Beryllium is a chemical element with the symbol Be and atomic number 4. It is a relatively rare element in the universe, usually occurring as a product of the spallation of larger atomic nuclei that have collided with cosmic rays. Within the cores of stars, beryllium is depleted as it is fused into heavier elements.  

Boron - Boron is a chemical element with the symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in the Solar System and in the Earth's crust. It constitutes about 0.001 percent by weight of Earth's crust.

Carbon - Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent-making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025 percent of Earth's crust.

Nitrogen - Nitrogen (N), nonmetallic element of Group 15 [Va] of the periodic table. It is a colorless, odorless, tasteless gas that is the most plentiful element in Earth's atmosphere and is a constituent of all living matter.

Fluorine - Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. As the most electronegative element, it is extremely reactive, as it reacts with all other elements, except for argon, neon, and helium.

Neon - Neon is a chemical element with the symbol Ne and atomic number 10. It is a noble gas. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

the ratio of the conjugate base to the acid required to attain the desired ph.