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Question: Answered & Verified by Expert
Assertion : $\mathrm{Yb}^{2+}$ is more stable as compare to $\mathrm{Gd}^{2+}$.
Reason : The electronic configuration of Gd is [ $\mathrm{Xe}] 4 f^7 5 d^2 6 s^2$.
Chemistryd and f Block ElementsAIIMSAIIMS 2019 (25 May)
Options:
  • A If both assertion and reason are true and reason is the correct explanation of assertion.
  • B If both assertion and reason are true but reason is not the correct explanation of assertion.
  • C If assertion is true but reason is false.
  • D If both assertion and reason are false.
Solution:
1714 Upvotes Verified Answer
The correct answer is: If assertion is true but reason is false.
$\begin{aligned} & \text { } \mathrm{Yb}^{2+}=[\mathrm{Xe}] 4 f^{14} 5 d^0 6 s^0 \\ & \mathrm{Gd}^{2+}=[\mathrm{Xe}] 4 f^7 5 d^1 6 s^0\end{aligned}$
Because of fully filled $4 f$ orbital, $\mathrm{Yb}^{2+}$ is more stable than $\mathrm{Gd}^{2+}$.

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