MCQ
Which of the following is not an actinide?
  • A
    Uranium
  • B
    Curium
  • C
    Californium
  • Erbium

Answer

Correct option: D.
Erbium
Erbium with atomic number 68, electronic configuration $[\mathrm{Xe}] 4 \mathrm{f}^{12} 6 \mathrm{s}^2$ belongs to lanthanides.
$\therefore$ Erbium is not an actinide.

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