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Chemistry · 2025 · 1 mark
CBSE 2025 · Region 7 · Set 2 · Q15
Assertion (A): Actinoids show irregularities in their electronic configurations. Reason (R): This is due to varying stability of f^0, f^7 and f^14…
Assertion (A) : Actinoids show irregularities in their electronic configurations.
Reason (R): This is due to varying stability of $\displaystyle \mathrm{f}^{0}, \mathrm{f}^{7}$ and $\displaystyle \mathrm{f}^{14}$ configurations.
Official answer
(A)
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
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CBSE Class 12 Chemistry past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.