Radon is

Radon (Rn) is a chemical element with atomic number 86, classified as a noble gas [1]. Noble gases are characterized by having a completely filled valence shell, which makes them chemically inactive or "inert" under standard conditions [1]. While other noble gases like Helium, Neon, and Argon are stable, Radon is a naturally occurring radioactive gas produced from the decay of uranium and thorium in the ground [2]. It is colorless, odorless, and tasteless. In the periodic table, noble gases occupy Group 18, representing the least reactive elements because they do not easily gain or lose electrons to attain a stable configuration [1]. Therefore, Radon is correctly identified as an inert gas, distinguishing it from metals, artificial fibers like rayon, or explosive chemical compounds.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.3 HOW DO METALS AND NON-METALS REA ALS REACT? > p. 46
2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Radioactivity: > p. 82