Which noble gas is the most abundant radioactive noble gas found naturally as a decay product of radium?

💡 Solution & Explanation

Radon is the heaviest and most naturally abundant radioactive noble gas, occurring as a direct gaseous decay intermediate in the radioactive disintegration chain of radium isotopes found in Earth's crust. Unlike chemically stable and non-radioactive noble gases such as xenon, krypton, or argon, radon is continuously emitted from rocks and soils containing uranium and thorium traces.