If a certain star shows a strong absorption spectrum in hydrogen Balmer lines,the surface temperature of the star is hot enough that collisions between atoms there:
A) ionize virtually all of the hydrogen atoms.
B) promote electrons in many hydrogen atoms to the n = 2 energy level.
C) promote electrons in many hydrogen atoms to the n = 3 energy level.
D) convert many helium atoms to hydrogen atoms.

Question

Quizplus · Accepted Answer

The hydrogen Balmer lines are produced when electrons in hydrogen atoms undergo transitions from higher energy levels to the n = 2 energy level. The fact that a strong absorption spectrum is seen in these lines indicates that there are many hydrogen atoms present in the outer layers of the star and that collisions are occurring that are exciting electrons to this level. However, the temperature is likely not hot enough to ionize all of the hydrogen atoms, and the n = 3 energy level is less likely to be populated than the n = 2 level. Helium is not converted into hydrogen during collisions, as they are two different elements.

If a Certain Star Shows a Strong Absorption Spectrum in Hydrogen