JEE Main & Advanced JEE Main Paper Phase-I (Held on 09-1-2020 Morning)

  • question_answer
    The electronic configurations of bivalent europium and trivalent cerium are (atomic number: Xe = 54, Ce = 58, Eu = 63)  [JEE MAIN Held on 09-01-2020 Morning]

    A) [Xe] \[4{{f}^{7}}\]and [Xe] \[4{{f}^{1}}\]

    B) [Xe] \[4{{f}^{7}}\]\[6{{s}^{2}}\] and [Xe] \[4{{f}^{2}}\text{ }6{{s}^{2}}\]

    C) [Xe] \[4{{f}^{2}}\]and [Xe] \[4{{f}^{7}}\]

    D) [Xe] \[4{{f}^{4}}\]and [Xe] \[4{{f}^{9}}\]

    Correct Answer: A

    Solution :

    [a] \[C{{e}^{3+}}\left( Z=58 \right)=\left[ Xe \right]4{{f}^{1}}\] \[E{{u}^{2+}}\left( Z=63 \right)-\left[ Xe \right]4{{f}^{7}}\]


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