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The d & f Block Elements — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryThe d & f Block Elements1 Mark
MCQ
The only radioactive element among the lanthanoids is:
  • A
    Gadolinium.
  • B
    Holmium.
  • ✓
    Promethium.
  • D
    Neodynium.
✓

Answer

Correct option: C.
Promethium.
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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