Which of the following is a characteristic of radon?

Radon is a naturally occurring gas that is produced from the decay of uranium in soil and rock. This characteristic is significant because it highlights radon's origin and its presence in the environment, often accumulating in homes, especially in lower levels such as basements. Being a gas at room temperature allows it to migrate through the ground and into buildings, which poses potential health risks due to its radioactive properties. Understanding that radon is a gas helps in recognizing the necessary precautions and remediation techniques to mitigate exposure.

The other options do not accurately describe radon: it is not a solid substance, it has a relatively short half-life compared to other radioactive elements, and it cannot be easily sensed without specialized equipment, as it is colorless, odorless, and tasteless.