What type of gas is radon?

Radon is classified as a natural radioactive gas, which is why this choice is the correct answer. It is a colorless, odorless gas produced from the natural decay of uranium found in soil, rock, and water. Due to its radioactive properties, radon can accumulate in buildings, particularly basements, and pose health risks, such as lung cancer, when inhaled over time.

The other options refer to various types of gases associated with kitchens or combustion processes. For example, cooking gases typically include propane or natural gas, neither of which is radioactive. Pressurized gases used in appliances relate to fuels that are specifically designed for energy use in cooking or heating but do not encompass the characteristics or natural origin of radon. Lastly, gases produced by combustion refer to products created when fuels are burned, such as carbon dioxide and water vapor, rather than naturally occurring gases like radon. Understanding the characteristics of radon as a naturally occurring radioactive element helps clarify why it fits the definition provided in the correct answer.