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JEE Main & Advanced Sample Paper JEE Main - Mock Test - 25

  • question_answer
    Which of the following factors may be regarded as the main cause of lanthanoid contraction?

    A) Greater shielding of 5d electrons by 4/electrons.

    B)        Poorer shielding of 5d electrons by 4/electrons.

    C)        Effective shielding of one of 4/electrons by another in the subshell.

    D)        Poor shielding of one of 4/electron by another in the subshell.

    Correct Answer: B

    Solution :

    In lanthanides, there is poorer shielding of 5d electrons by 4f electrons resulting in greater attraction of the nucleus over 5d electrons and contraction of the atomic radii.


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