Answer: thoron

AnswerCrossword Clue
THORONIsotope of radon
THORONHeavy gas
THORONRadioactive isotope
THORONRadon isotope
thorona radioactive isotope of radon
thoronradioactive isotope of radon, produced by the disintegration of thorium. Symbol: Tn; at. wt.: 220; at. no.: 86