As the Universe has evolved,____________.
A) hydrogen has been lost through fusion to form helium within stars
B) hydrogen concentration has increased through the fission of helium atoms
C) hydrogen concentration has increased through the fusion of helium atoms
D) the number of hydrogen atoms has likely remained constant

Question

Quizplus · Accepted Answer

Hydrogen atoms have been lost through fusion to form helium within stars during the process of stellar nucleosynthesis. This conversion of hydrogen into helium is the primary energy source in stars and has been happening since the earliest stars formed. Therefore, the concentration of hydrogen in the universe has been decreasing over time.

As the Universe Has Evolved,____________