Which gas is most abundant in the Sun?

The most abundant gas in the Sun is hydrogen. It constitutes about 74% of the Sun's mass and plays a crucial role in the processes occurring within the Sun, particularly in nuclear fusion. During nuclear fusion, hydrogen nuclei (protons) combine under extreme heat and pressure to form helium, releasing enormous amounts of energy in the process. This energy is what powers the Sun and provides light and heat to the solar system.

While helium is also present in the Sun and is the second most abundant element, it comprises only about 24% of the Sun's mass. The other gases listed, such as nitrogen and oxygen, are present in negligible amounts compared to hydrogen and helium. Therefore, hydrogen's predominance as the primary fuel for the Sun's energy production and its contribution to its overall mass establishes it as the correct answer.