NEET Chemistry Redox Reactions / रेडॉक्स अभिक्रियाएँ NEET PYQ-Redox Reactions

  • question_answer
    Oxidation numbers of P in \[PO_{3}^{4-}\] of S in  \[SO_{3}^{2-}\] and that of Cr in \[C{{r}_{2}}O_{7}^{2-}\] are respectively,                                                                                                       [AIPMT (S) 2009]

    A) +5, +6 and +6

    B)  +3, +6 and +5

    C)  +5, +3 and +6

    D)       -3, +6 and +6

    Correct Answer: A

    Solution :

    Key Idea (i) Sum of oxidation states of all atoms = charge of ion.
    (ii) Oxidation number of oxygen = - 2.
    Let the oxidation state of P in \[{{C}_{2}},{{C}_{3}},{{C}_{5}}\]is x.
    \[{{C}_{6}}\]
    \[{{F}_{2}}\]\[B{{r}_{2}}\]
       \[{{I}_{2}}\]
    \[C{{l}_{2}}\]
    Let the oxidation state of S in \[\frac{M}{32}\] is y.
    \[1.25\times {{10}^{-5}}\]
    \[1.25\times {{10}^{-6}}\]\[6.25\times {{10}^{-4}}\]
    \[1.25\times {{10}^{-4}}\]
    \[-C{{F}_{2}}-C{{F}_{2}}-{{)}_{n}}\]
    Let the oxidation state of Cr in \[{{\left( -C{{H}_{2}}-\underset{\begin{smallmatrix}  | \\  Cl \end{smallmatrix}}{\mathop{C}}\,=CH-C{{H}_{2}}-C{{H}_{2}}- \right)}_{n}}\] is z.
    \[-{{[NH{{(C{{H}_{2}})}_{6}}NHCO{{(C{{H}_{2}})}_{4}}-CO-]}_{n}}\]
    \[PO_{4}^{3-},\]\[SO_{4}^{2-}\]
    \[C{{r}_{2}}O_{7}^{2-}\]
    \[CH\equiv C-CH=C{{H}_{2}}\]
    Hence, oxidadon state of P, S and Cr are +5, + 6 and + 6 respectively.


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