Is it possible for two or more elements to have the same number of protons? Why?

No

Explanation:

Hello!

Only one element can have the same number of protons.

Proton amount is basically like the DNA of a proton; it makes them what they are.

When elements are isotopes instead, their neutron count changes but their protons remain the same.

For example, all carbons have 6 protons regardless of if they are an isotope or not. A carbon-12 and a carbon-14 will still have 6 protons, but different amount of neutrons.

the answer is na (sodium)

oxygen, selenium, tellurium, and polonium.

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