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Chemistry · 2026 · 1 mark
CBSE 2026 · Region 3 · Set 2 · Q13
Assertion (A): Separation of Zr and Hf is difficult. Reason (R): Zr and Hf have almost identical atomic and ionic radii due to lanthanoid contraction.
Assertion (A) : Separation of Zr and Hf is difficult. Reason $\displaystyle (R)$ : Zr and Hf have almost identical atomic and ionic radii due to lanthanoid contraction.
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 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.