Which of the following actinoids exhibits only $+3$ oxidation state

Which of the following actinoids exhibits only $+3$ oxidation state
  1. $\operatorname{Lr}(\mathrm{z}=103)$
  2. $U(z=92)$
  3. $Th(z=90)$
  4. $Pa(z=91)$

Solution

$\operatorname{Lr}(Z=103)=[R n] 5 f^{4} 6 d^{1} 7 s^{2}$ Due to completely filled $5 \mathrm{f}-$ orbital, $\mathrm{Lr}$ exhibits only $+3$ oxidation state.

Asked in: MHT CET 2020 (16 Oct Shift 2)

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