According to the properties of f-block elements, "The behaviour of samarium is very much like europium, exhibiting both +2 and +3 oxidation states" . Also, the electronic configuration of samarium ($Z=62$) is $[Xe] 4f^6 6s^2$ and that of europium ($Z=63$) is $[Xe] 4f^7 6s^2$ . Thus, the given electronic configuration options are incorrect. Their atomic radii also differ (Sm = 180 pm, Eu = 199 pm) .