The dand fblock elements - Result Question 72
####72. The electronic configurations of $Eu($ Atomic No. 63), Gd(Atomic No. 64) and Tb (Atomic No. 65) are
[2016]
(a) $[X e] 4 f^{7} 6 s^{2},[X e] 4 f^{8} 6 s^{2}$ and $[X e] 4 f^{8} 5 d^{1} 6 s^{2}$
(b) $[X e] 4 f^{7} 5 d^{1} 6 s^{2},[X e] 4 f^{7} 5 d^{1} 6 s^{2}$ and $[X e] 4 f^{9} 6 s^{2}$
(c) $[X e] 4 f^{6} 5 d^{1} 6 s^{2},[X e] 4 f^{7} 5 d^{1} 6 s^{2}$ and $[X e] 4 f^{8} 5 d^{1} 6 s^{2}$
(d) $[X e] 4 f^{7} 6 s^{2},[X e] 4 f^{7} 5 d^{1} 6 s^{2}$ and $[X e] 4 f^{9} 6 s^{2}$
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Solution:
- (d) $Eu(63)=[Xe] 4 f^{7} 6 s^{2}$
$Gd(64)=[Xe] 4 f^{7} 5 d^{1} 6 s^{2}$
$Tb(65)=[Xe] 4 f^{9} 6 s^{2}$
