Radon has natural origins and is a colorless, odorless, radioactive gas that's released when ______ decays.

Radon is indeed a naturally occurring, colorless, odorless, and radioactive gas. It is produced through the decay of uranium, which is found in soil, rocks, and even in some water supplies. The process involves the decay of uranium-238 into radon-222. This decay process is part of a larger chain reaction that can also involve other radioactive elements, but the initial source leading to radon formation is specifically uranium.

While other elements like radium and thorium can also be part of the decay chains that lead to radon, uranium is the primary element associated with the direct production of radon. Understanding this relationship is critical for recognizing radon’s presence in various environments, especially in homes built on soil with high uranium content.