How can multiple colors of light be seen from a hydrogen gas discharge tube?

The correct answer is based on the concept of excited hydrogen atoms undergoing different electronic transitions. In a hydrogen gas discharge tube, hydrogen atoms are excited by an electric current, elevating electrons to higher energy levels. When the electrons return to their lower energy states, they release energy in the form of light.

Each transition between energy levels corresponds to a specific wavelength of light, producing distinct colors. As there are various energy levels in hydrogen, different atoms can undergo various transitions, resulting in a mix of colors observed. This phenomenon accounts for the multiple colors emitted when hydrogen gas is excited.

The other options do not accurately capture the underlying physics of the situation. For instance, individual atoms do not emit multiple colors simultaneously as suggested, since each atom releases light corresponding to a specific transition only. While refraction and dispersion through glass could separate colors, this is not the mechanism at play in a discharge tube scenario. Finally, the assumption that multiple hydrogen atoms make the same transition does not account for the fact that the quantity and combinations of transitions result in a spectrum seen. Thus, the observation of multiple colors is primarily due to different hydrogen atoms making different electronic transitions.