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CET Karnataka Medical CET - Karnataka Medical Solved Paper-2014

  • question_answer
    The correct arrangement for the ions in the increasing order of their radii is

    A)  \[N{{a}^{+}},C{{l}^{-}},C{{a}^{2+}}\]

    B)  \[C{{a}^{2+}},{{K}^{+}},{{S}^{2-}}\]

    C)  \[N{{a}^{+}},A{{l}^{3+}},B{{e}^{2+}}\]

    D)  \[C{{l}^{-}},{{F}^{-}},{{S}^{2-}}\]

    Correct Answer: B

    Solution :

    :
    Species    At No.    No. of \[{{e}^{-}}\]
    \[C{{a}^{2+}}\]        20         18
    \[{{K}^{+}}\]         19           18
    \[{{S}^{2-}}\]        16           18
    The species \[C{{a}^{2+}},\] \[{{K}^{+}}\] and \[{{S}^{2-}}\] are isoelectronic. For isoelectronic ions, the radius decreases as the nuclear charge increases. Hence, the increasing order of their radii is \[C{{a}^{2+}}<{{K}^{+}}<{{S}^{2-}}\]


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