Question

21. _______________ is an example of radioactive element with atomic number less than 82​

Answer 1

Answer:

actinide

The elements present in the actinide series are radioactive elements. Actinide series starts from the element thorium having the atomic number 90. Hence, elements having the atomic number greater than 82 are radioactive.

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Answer 2

Answer:

Actinide series starts from the element thorium having the atomic number 90. Hence, elements having the atomic number greater than 82 are radioactive elements.