Which of the following BEST describes radon?
A colorless, odorless gas that can attach to dust particles and can cause certain cancers.
It was commonly used as insulation in the 19th century. It has since been outlawed as it is linked to lung cancer.
It is a colorless, odorless gas which binds to particles in the blood and can be fatal.
It is a dense metallic element that can cause developmental delays in humans.
It is a colorless, odorless gas which is an organic compound by plants to make sugars.