The d & f Block Elements — Chemistry STD 12 Science — Question
Rajasthan BoardEnglish MediumSTD 12 ScienceChemistryThe d & f Block Elements1 Mark
Question
The only radioactive element among the lanthanoids is:
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Answer
Promethium.
Explanation:
Promethium is a lanthanoid element with the symbol Pm and atomic number 61. All of its isotopes are radioactive. Gadolinium, holmium and neodynium are lanthanoids but are not radio active.
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