Radioactivity
/rˈeɪdioʊˌæˌktɪvəˌti/
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Definition
(noun) Spontaneous emission of ionizing radiation as a consequence of a nuclear reaction, or directly from the breakdown of an unstable nucleus.
Sentence Examples
The radioactivity leaked out of the nuclear power plant.
'Radioactivity' is a chemical term.
CEFR Practice Quiz
The level of ____ in the soil near the old plant was found to be above safe limits.