AMU Medical AMU Solved Paper-2002

  • question_answer
    The   oxidation   number   of   C   in \[C{{H}_{4}},C{{H}_{3}}Cl,C{{H}_{2}}C{{l}_{2}},CHC{{l}_{3}}\] and \[CC{{l}_{4}}\] is respectively

    A)  -4, -2, 0, +2, +4

    B)  +2, 4, 0, -2, -4  

    C)  4, 2, 0, -2, -4

    D)  0, 2, -2, 4, 4

    Correct Answer: A

    Solution :

                     Key Idea The O.N. of hydrogen is +1 when combined with non-metals and is -1 when combined with active metals called metal hydrides. The O.N. of monoatomic ion \[(C{{N}^{-}})\] is same as the charge on it, so the O.N. of chlorine is -1. Let the oxidation number of C is x. \[\Rightarrow \]               \[C{{H}_{4}}\]                                 \[x+4\,(+1)=0\]                                                 \[x=-4\] \[\Rightarrow \]               \[C{{H}_{3}}Cl\]                                 \[x+3\,(+1)+(-1)=0\]                                                 \[x+3-1=0\]                                                                 \[x=-2\] \[\Rightarrow \]               \[C{{H}_{2}}C{{l}_{2}}\]                                 \[x+2(+1)+2(-1)=0\]                                                 \[x=0\] \[\Rightarrow \]               \[CHC{{l}_{3}}\]                                 \[x+(+1)+3(-1)=0\]                                                 \[x+1-3=0\]                                                                 \[x=2\] \[\Rightarrow \]               \[CC{{l}_{4}}\]                                 \[x+4(-1)=0\]                                                 \[x=+4\] Therefore, the O.N. of C in\[C{{H}_{4}},C{{H}_{3}}Cl,C{{H}_{2}}C{{l}_{2}},CHC{{l}_{3}}\] and \[CC{{l}_{4}}\] are    -4, - 2, 0, + 2, + 4 respectively.


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