NEET Chemistry Chemical Bonding and Molecular Structure / रासायनिक आबंधन एवं आणविक संरचना NEET PYQ-Chemical Bonding Molecular

  • question_answer
    Which of the following options represents the correct bond order?                                           [NEET 2015 ]

    A)  \[O_{2}^{-}>{{O}_{2}}>O_{2}^{+}\]   

    B)     \[O_{2}^{-}<{{O}_{2}}<O_{2}^{+}\]

    C)  \[O_{2}^{-}>{{O}_{2}}<O_{2}^{+}\]    

    D)       \[O_{2}^{-}<{{O}_{2}}>O_{2}^{+}\]

    Correct Answer: D

    Solution :

    Bond order of \[O_{2}^{-}\]
    \[O_{2}^{-}=\sigma 1{{s}^{2}},\overset{*}{\mathop{\sigma }}\,1{{s}^{2}},\sigma 2{{s}^{2}}\overset{*}{\mathop{\sigma }}\,2{{s}^{2}}\sigma 2p_{z}^{2}(\pi 2p_{x}^{2}=\pi 2p_{y}^{2})\]\[({{\pi }^{*}}2p_{x}^{2}={{\pi }^{*}}2p_{y}^{1})\]
    Bond order
    \[\frac{\text{number of electrons in BMO - number of elections ABMO}}{2}\]\[=\frac{10-7}{2}=\frac{3}{2}=1.5\]
    \[O_{2}^{+}=\sigma 1{{s}^{2}},\overset{*}{\mathop{\sigma }}\,1{{s}^{2}},\sigma 2{{s}^{2}},\overset{*}{\mathop{\sigma }}\,2{{s}^{2}}\sigma 2p_{z}^{2}\]
                \[(\pi 2p_{x}^{2}=\pi 2p_{y}^{2})({{\pi }^{*}}2p_{x}^{1}={{\pi }^{*}}2p_{y}^{0})\]
    \[BO=\frac{10-5}{2}=\frac{5}{2}=2.5\]
    \[{{O}_{2}}=\sigma 1{{s}^{2}}\overset{*}{\mathop{\sigma }}\,1{{s}^{2}},\sigma 2{{s}^{2}},\overset{*}{\mathop{\sigma }}\,2{{s}^{2}}\sigma 2p_{z}^{2}\,\,\,\,(\pi 2p_{x}^{2}=\pi 2p_{y}^{2})\]              \[(\overset{*}{\mathop{\pi }}\,2p_{x}^{1}=\overset{*}{\mathop{\pi }}\,2p_{y}^{1})\]
    \[BO=\frac{10-6}{2}=\frac{4}{2}=2\]
    So, the correct sequence is
    \[O_{2}^{-}<{{O}_{2}}<O_{2}^{+}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner