While is the dominant and universally stable oxidation state for the inner transition elements, cert — d and f Block Elements Chemistry Question

💡 Solution & Explanation

The variability of oxidation states in Lanthanides ($+2, +4$) occurs almost exclusively when the resulting ion can achieve an $f^0$ (empty), $f^7$ (half-filled), or $f^{14}$ (fully filled) subshell. $Ce^{4+}$ ($Z=58$) is $4f^0$. $Yb^{2+}$ ($Z=70$) is $4f^{14}$. $Eu^{2+}$ ($Z=63$) is $4f^7$. $Tb^{4+}$ ($Z=65$, ground state $[Xe] 4f^9 6s^2$) loses 4 electrons to become exactly $4f^7$. All statements are absolutely correct.