Q. By which of the following process some stars which are of the size of Sun or smaller convert hydrogen to helium?
Answer: Proton Proton Chain Reaction
Notes: The correct answer is the Proton Proton Chain Reaction. This process occurs in stars like the Sun, where hydrogen nuclei (protons) fuse to form helium, releasing energy. It is the dominant energy production mechanism in stars with masses similar to or smaller than the Sun. The CNO cycle, on the other hand, is more prevalent in larger stars. The proton-proton chain reaction is responsible for about 99% of the Sun's energy output.