Q. The noble gas used for the treatment of cancer is _____:
Answer:
Radon
Notes: Radon was once commonly used to treat cancer. The radiation it gives off kills cancer cells. However, the element must be used with great care because radiation can kill healthy cells as well. In fact, the bad side-effects of radiation therapy are caused by the killing of healthy cells by radiation. Today, radon is not as widely used for the treatment of cancer.