JCECE Medical JCECE Medical Solved Paper-2012

  • question_answer
    A   solution   of sucrose (molar  \[\text{mass}=342\,\text{g}\,\text{mo}{{\text{l}}^{-1}}\]) has been prepared by  dissolving 68.5 g of sucrose in 1000 g of water. The freezing point of solution obtained will be (\[{{k}_{f}}\]for water\[=\text{1}\text{.86}\,\text{K}\,\text{kg}\,\text{mo}{{\text{l}}^{-1}}\])

    A) \[-\text{ }0.570{{\,}^{o}}C\]    

    B) \[~-0.372{{\,}^{o}}C\]

    C) \[~-0.520{{\,}^{o}}C\]

    D) \[~+\,0.372{{\,}^{o}}C\]

    Correct Answer: B

    Solution :

     \[\Delta {{T}_{f}}=\frac{1000\times {{K}_{f}}\times {{w}_{2}}}{{{M}_{2}}\times {{w}_{1}}}\] \[=\frac{1000\times 1.86\times 68.5}{342\times 1000}\] \[=0.372{{\,}^{o}}C\] \[\Delta {{T}_{f}}=T_{f}^{o}-\Delta {{T}_{f}}\] \[=0-0.372=-0.372{{\,}^{o}}C\]


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