Why are the Balmer lines of hydrogen weak in stars that are hotter than about 10,000 K?
A)Hydrogen is mostly ionized in hot stars
B)Hot stars are made mostly of helium
C)Most hydrogen atoms are in the ground state in hot stars
D)Most hydrogen is in molecular form in hot stars

Question

Quizplus · Accepted Answer

The Balmer lines of hydrogen arise from electron transitions between energy levels in the hydrogen atom, with the strongest line being the transition from the second to the third energy level (H-alpha). In hot stars, the temperature is high enough to ionize most of the hydrogen atoms, eliminating the electrons necessary for these transitions and making the Balmer lines weak.

Why Are the Balmer Lines of Hydrogen Weak in Stars