Concept:Radon is a noble gas from Group 18 of the periodic table, known for being chemically unreactive.
Explanation:Group 18 elements are helium, neon, argon, krypton, xenon, and radon.
All are monatomic gases with a full valence shell, making them inert.
Radon is radioactive and forms very few compounds.
It is produced as a decay product of radium-226 (
226Ra).
Most noble gases occur in the air, but radon is found underground from radioactive decay.
Answer:An inert gas.