Which noble gas is the most abundant in the universe? In Earth atmosphere?
The correct answer and explanation is :
The most abundant noble gas in the universe is helium (He), while the most abundant noble gas in Earth’s atmosphere is argon (Ar).
Explanation:
Helium in the Universe
Helium is the second most abundant element in the universe, after hydrogen. It constitutes about 24% of the universe’s elemental mass. The primary reason for helium’s abundance is that it was formed during the Big Bang nucleosynthesis, where hydrogen atoms fused to form helium. Additionally, helium is continuously produced in stars through nuclear fusion, where hydrogen atoms fuse to form helium under extreme pressure and temperature. This process is responsible for the immense supply of helium throughout the universe, particularly in stars, including our Sun.
Argon in Earth’s Atmosphere
In contrast to the universe, the most abundant noble gas in Earth’s atmosphere is argon (Ar), making up about 0.93% of the air by volume. Argon is more abundant than other noble gases, such as neon (Ne) and helium, because it is continuously released into the atmosphere through the radioactive decay of potassium-40 (K-40) in Earth’s crust. Potassium-40 undergoes decay to produce argon-40, which then accumulates in the atmosphere over geological time.
Although helium is present in Earth’s atmosphere, it is much less abundant (about 0.0005% by volume) because its low atomic mass allows it to escape Earth’s gravity into space. Unlike helium, argon is heavier and remains trapped in the atmosphere.
Thus, while helium dominates the universe, argon is the most prevalent noble gas on Earth due to its stable production and retention in the atmosphere.