Punjab Medical Punjab - MET Solved Paper-2010

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

    A) \[-4,\,\,-2,\,\,+2,\,\,0,\,\,+4\]   

    B) \[+2,\,\,4,\,\,0,\,\,-2,\,\,-4\]

    C) \[+4,\,\,+0,\,\,-2,\,\,-2,\,\,+4\] 

    D) \[0,\,\,2,\,\,-2,\,\,4,\,\,4\]

    Correct Answer: A

    Solution :

    Let the oxidation number of C is x. \[\underset{\begin{smallmatrix}  x+4\times (+1)=0 \\  \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x=-4 \end{smallmatrix}}{\mathop{C{{H}_{4}}}}\,\]                     \[\underset{\begin{smallmatrix}  x+3(+1)-1=0 \\  \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x=-2 \end{smallmatrix}}{\mathop{C{{H}_{3}}Cl}}\,\] \[\underset{\begin{smallmatrix}  x+1+3\times (-1)=0 \\  \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x=+2 \end{smallmatrix}}{\mathop{CHC{{l}_{3}}}}\,\]                  \[\underset{\begin{smallmatrix}  x+2\times (+1)+2\times (-1)=0 \\  \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x=0 \end{smallmatrix}}{\mathop{C{{H}_{2}}C{{l}_{2}}}}\,\] \[\underset{\begin{smallmatrix}  x+4\times (-1)=0 \\  \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x=+4 \end{smallmatrix}}{\mathop{CC{{l}_{4}}}}\,\] Hence, the oxidation number of\[C\]in\[C{{H}_{4}}\], \[C{{H}_{4}},\,\,C{{H}_{3}}Cl,\,\,CHC{{l}_{3}},\,\,C{{H}_{2}}C{{l}_{2}}\]and\[CC{{l}_{4}}\]is respectively \[-4,\,\,-2,\,\,+2,\,\,0\]and\[+4\].


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