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JEE Main & Advanced Chemistry Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ Question Bank Critical Thinking

  • question_answer
    Complete combustion of \[0.858\ g\] of compound X gives \[2.63\ g\] of \[C{{O}_{2}}\] and \[1.28\ g\] of \[{{H}_{2}}O\]. The lowest molecular mass X can have                                   [Kerala MEE 2000]

    A)                 \[43\ g\]  

    B)                 \[86\ g\]

    C)                 \[129\ g\]               

    D)                 \[172\ g\]

    Correct Answer: A

    Solution :

               \[%C=\frac{12}{44}\times \frac{{{W}_{C{{O}_{2}}}}}{W}\times 100\]\[=\frac{12}{44}\times \frac{2.63}{0.858}\times 100=83.6%\]                    \[%H=\frac{2}{18}\times \frac{{{W}_{{{H}_{2}}O}}}{W}\times 100\]\[=\frac{2}{18}\times \frac{1.28}{.858}\times 100=16.4%\] \[\left. \begin{matrix}    Element & %\left( a \right) & At.wt.\left( b \right) & a/b & Ratio  \\    C & 83.6 & 12 & 6.96 & 1  \\    H & 16.4 & 1 & 16.4 & 2.3  \\ \end{matrix} \right]\times {{3}_{_{_{_{_{_{_{_{_{_{_{_{_{_{_{_{7}}}}}}}}}}}}}}}}}\]                                 \[{{C}_{3}}{{H}_{7}}=12\times 3+7=43gm\].


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