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Chemistry · 2026 · 1 mark
CBSE 2026 · Region 1 · Set 2 · Q14
Assertion (A): Actinoids show irregularities in their electronic configurations. Reason (R): In actinoids 5f, 6d and 7s orbitals are of comparable…
Assertion (A) : Actinoids show irregularities in their electronic configurations.
Reason (R) : In actinoids 5f, 6d and 7s orbitals are of comparable energies.
Official answer
(B)
Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
All The d-and f-Block Elements questions2026 question paperNCERT solutions: The d-and f-Block ElementsPractice The d-and f-Block Elements →
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CBSE Class 12 Chemistry past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.