Lanthanoids – electronic configuration

2016 1 question

1. 1 The d- and f-Block Elements
   The electronic configurations of Eu (Atomic no. 63), Gd (Atomic no. 64) and Tb (Atomic no. 65) are
   A $[Xe]4f^65d^16s^2$, $[Xe]4f^75d^16s^2$ and $[Xe]4f^96s^2$ B $[Xe]4f^65d^16s^2$, $[Xe]4f^75d^16s^2$ and $[Xe]4f^85d^16s^2$ C $[Xe]4f^76s^2$, $[Xe]4f^75d^16s^2$ and $[Xe]4f^96s^2$ D $[Xe]4f^76s^2$, $[Xe]4f^86s^2$ and $[Xe]4f^85d^16s^2$
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