CMC Medical CMC-Medical VELLORE Solved Paper-2014

  • question_answer
    Peroxide ion
    I. has five completely filled anti-bonding molecular orbitals
    II. is diamagnetic
    III. has bond order one
    IV. is isoelectronic with neon
    Which of these are correct?

    A)  II and III              

    B)  I, II and IV

    C)  I, III and IV                        

    D)  I and IV

    Correct Answer: A

    Solution :

              Peroxide ion is\[O_{2}^{2-}.\] \[O_{2}^{2-}(18)=\sigma 1{{s}^{2}},\overset{*}{\mathop{\sigma }}\,1{{s}^{2}},\sigma 2{{s}^{2}},\overset{*}{\mathop{\sigma }}\,2{{s}^{2}},\sigma 2p_{z}^{2}\] \[\pi 2p_{x}^{2}\approx \pi 2p_{y}^{2},\overset{*}{\mathop{\pi }}\,2p_{x}^{2}\approx \overset{*}{\mathop{\pi }}\,2p_{y}^{2}\] Bond order\[=\frac{{{N}_{b}}-{{N}_{a}}}{2}\] \[=\frac{10-8}{2}=1\] It contains four completely filled anti bonding molecular orbitals. Since, all the electrons are paired,\[O_{2}^{2-}\]is diamagnetic. Peroxide ion is isoelectronic with argon, not with neon.


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