The most abundant rare gas in the atmosphere is Argon (Ar).
Rare gases, also known as noble gases, are a group of chemical elements that are found in the atmosphere in small amounts. The rare gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Of these, argon is the most abundant, making up approximately 0.934% of the Earth's atmosphere.
Argon is an odorless, colorless, and tasteless gas that is chemically inert, meaning it does not easily react with other chemical species. This makes it useful in a variety of industrial and scientific applications, such as in the production of electric lamps and in welding. Despite its abundance, argon is still considered a rare gas because it is relatively scarce compared to other atmospheric gases, such as nitrogen and oxygen, which make up the majority of the Earth's atmosphere.