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NEET Chemistry The d-and f-Block Elements / d तथा f ब्लॉक के तत्व Question Bank Self Evaluation Test - The d-and f-Block Elements

  • question_answer
    Arrange (I) \[C{{e}^{3+}}\], (II) \[L{{a}^{3+}}\], (III) \[P{{m}^{3+}}\], and (IV) \[Y{{b}^{3+}}\] in increasing order of their ionic radii.

    A) IV<III<I<II      

    B) I<IV<III<II

    C) IV<III<II<I      

    D) III<II<I<IV

    Correct Answer: A

    Solution :

    [a] Ionic radii decrease across lanthanide series due to lanthanide contraction. As all ions are in +3 O.S., ionic radii will follow the trend of atomic radii. \[\therefore \underset{\left( Z=57 \right)}{\mathop{L{{a}^{3+}}}}\,>\underset{(Z=58)}{\mathop{C{{e}^{3+}}}}\,>\underset{(Z=61)}{\mathop{P{{m}^{3+}}}}\,>\underset{(Z=70)}{\mathop{Y{{b}^{3+}}}}\,\]


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