The dand fblock elements - Result Question 9
####9. Which of the following lanthanoid ions is diamagnetic?
(At nos. $Ce=58, Sm=62, Eu=63, Yb=70$ )
[NEET 2013]
(a) $Sm^{2+}$
(b) $Eu^{2+}$
(c) $Yb^{2+}$
(d) $Ce^{2+}$
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Solution:
- (c) $Sm^{2+}(Z=62)$
$[Xe] 4 f^{6} 6 s^{2}-6$ unpaired $e^{-}$
$Eu^{2+}(Z=63)$
$[Xe] 4 f^{7} 6 s^{2}-7$ unpaired $e^{-}$
$Yb^{2+}(Z=70)$
$[Xe] 4 f^{14} 6 s^{2}-0$ unpaired $e^{-}$
$Ce^{2+}(Z=58)$
$[Xe] 4 f^{1} 5 d^{1} 6 s^{2}-2$ unpaired $^{-}$
Only $Yb^{2+}$ is diamagnetic.
