What is the name of the colorless, odorless radioactive gas that is a byproduct of uranium in the soil?

The correct answer is radon, which is a colorless and odorless gas that forms from the natural decay of uranium found in soil and rock. As uranium breaks down, it releases radon gas, which can accumulate in homes, especially in basements and poorly ventilated areas. Radon is significant because it poses health risks, particularly as a leading cause of lung cancer for non-smokers. Understanding the presence of radon is crucial for real estate professionals, particularly those involved in home sales, as they must inform clients about potential radon exposure and the importance of testing for it in properties.

The other gases listed, while also colorless and odorless, are not produced from uranium decay and do not carry the same health implications associated with radon. Xenon, krypton, and argon are noble gases that do not present the same risks that radon does, making radon distinct in this context.