NEET Solved Paper 2016 Question 15
Question: The electronic configurations of Eu(Atomic No 63), Gd(Atomic No 64) and Tb (Atomic No. 65) are
Options:
A) $ [Xe]4f^{7}6s^{2},\text{ }[Xe]4f^{8}6s^{2} $ and $ [Xe]4f^{8}5d^{1}6s^{2} $
B) $ [Xe]4f^{7}5d^{1}6s^{2},\text{ }[Xe]4f^{7}5d^{1}6s^{2} $ and $ [Xe]4f^{9}6s^{2} $
C) $ [Xe]4f^{6}5d^{1}6s^{2},\text{ }[Xe]4f^{7}5d16s^{2} $ and $ [Xe]4f^{8}5d^{1}6s^{2} $
D) $ [Xe]4f^{7}6s^{2},\text{ }[Xe]4f^{7}5d^{1}6s^{2} $ and $ [Xe]4f^{9}6s^{2} $
Show Answer
Answer:
Correct Answer: D
Solution:
The electronic configuration of Eu(Atomic No. 63), Gd(Atomic No. 64) and Tb(Atomic No. 65) are :
$[Xe]4f7s^2$, $[Xe]4f75d16s^2$ and $[Xe]4f96s^2$respectively.
Gd possesses a single electron in the 5d subshell. In the case of other lanthanoids, the 5d orbital is empty.
Hence, the correct option is D.
