Answer: Radon
Notes: Radon, a radioactive noble gas with atomic number 86, is used in radiotherapy. Created by disintegration of radium, its one of the heaviest gases and a health hazard. Radon gas, chemically inert yet radioactive, can accumulate in buildings and drinking water causing lung cancer. Furthermore, radon is noted for brilliant phosphorescence when cooled below its freezing point. Its most stable isotope, 222Rn, has a half-life of 3.8 days. Groundwater often has a higher 222Rn concentration than surface water due to less exposure to atmosphere.
This Question is Also Available in:
हिन्दी
This question has been sourced from GKToday's "40000+ GK / General Studies MCQs for SSC & State PCS Exams" App Exclusive Course in
GKToday Android Application which provides more than 40K General Knowledge and General Studies questions with explanations asked in all Competitive Exams of India.