CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2008

  • question_answer
    In which of the following the oxidation number of oxygen has been arranged in increasing order?

    A) \[O{{F}_{2}}<K{{O}_{2}}<Ba{{O}_{2}}<{{O}_{3}}\]

    B) \[Ba{{O}_{2}}<K{{O}_{2}}<{{O}_{3}}<O{{F}_{2}}\]

    C) \[Ba{{O}_{2}}<{{O}_{3}}<O{{F}_{2}}<K{{O}_{2}}\]

    D) \[K{{O}_{2}}<O{{F}_{2}}<{{O}_{3}}<Ba{{O}_{2}}\]

    E)  \[O{{F}_{2}}<{{O}_{3}}<K{{O}_{2}}<Ba{{O}_{2}}\]

    Correct Answer: B

    Solution :

    Let the oxidation number of oxygen in following compounds is\[x\]. In \[O{{F}_{2}}\] \[x+(-1)2=0\] \[x=+2\]                 In \[K{{O}_{2}}\]                 \[+1+(x\times 2)=0\]                 \[2x=-1\]                 \[x=-\frac{1}{2}\]                 In \[Ba{{O}_{2}}\]                 \[+2+(x\times 2)=0\]                 \[2x=-2\]                 \[x=-1\] In\[{{O}_{3}},\]oxidation number of oxygen is zero because oxidation number of an element in Free State or in any of its allotropic form is always zero. Thus, the increasing order of oxidation number is                 \[\begin{align}   & Ba{{O}_{2}}<K{{O}_{2}}<{{O}_{3}}<O{{F}_{2}} \\  & -1\,\,\,\,\,\,\,\,\,\,\,\,\,-\frac{1}{2}\,\,\,\,\,\,\,\,\,\,0\,\,\,\,\,\,\,+2 \\ \end{align}\]


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