Which hazardous gas is colorless and odorless, found in soil, and can seep into homes?

Radon is a colorless and odorless radioactive gas that originates from the natural decay of uranium in soil, rock, and water. It can seep into homes through cracks in floors, walls, and foundations, as well as through gaps around service pipes and in some cases, water supply. Because radon is undetectable by human senses—lacking both color and smell—it poses a significant health risk as prolonged exposure can lead to lung cancer.

Understanding the properties of radon is crucial for homeowners and prospective buyers, particularly in areas where uranium is prevalent in the soil. Testing for radon levels is essential for ensuring a safe living environment. The other options, while they may pose risks in certain circumstances, do not share the same attributes of being a colorless and odorless gas that can specifically seep into homes from soil.