What evidence leads us to believe that energy levels in the hydrogen atom are quantities?

Because only certain photons are emitted, we know that only certain energy changes are occurring. This means that the hydrogen atom must have certain discrete energy levels. Excited hydrogen atoms always emit photons with the same discrete colors (wavelengths). They never emit photons with energies between those shown. So we concluded, all hydrogen atoms have the same set of discrete energy levels.

Explanation:

unit 4 test (i have all the answers if you want me to send the link i can)

since electrons are negative the answer is neagtaive