Question
Define radioactivity.
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Answer
Radioactivity : The phenomenon of spontaneous disintegration of atoms is called radioactivity. In 1896 AD , French scientist Becquerel discovered that some invisible rays automatically emitted from uranium and its salts, which have the ability to penetrate opaque materials and affect the photographic plate. These rays are called radioactive rays. The phenomenon of a substance emitting rays spontaneously is called 'radioactivity' and such a substance is called 'radioactive substance'. After the discovery of the property of radioactivity in uranium, it became known that not only uranium but other elements like thorium, polodium, actinium etc. are also radioactive.
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