AIIMS AIIMS Solved Paper-2006

  • question_answer
     A 5% solution (by mass) of cane sugar in water has freezing point of 271 K and freezing point of pure water is 273.15 K. The freezing point of a 5% solution (by mass) of glucose in water is:

    A)  271 K                   

    B)         273.15 K             

    C)         269.07 K             

    D)         277.23 K

    Correct Answer: C

    Solution :

    \[\Delta {{T}_{f}}={{K}_{f}}\times \frac{w}{m}\times \frac{1000}{W}\] \[\frac{\Delta {{T}_{f2}}}{\Delta {{T}_{f1}}}=\frac{{{m}_{1}}}{{{m}_{2}}}\] Here, \[{{m}_{1}}\] (cane sugar \[{{C}_{12}}{{H}_{22}}{{O}_{11}}\]) \[=342\] \[{{m}_{2}}\] (glucose \[{{C}_{6}}{{H}_{12}}{{O}_{6}}\]) \[=180\]) \[\Delta {{T}_{f1}}=273.15-271\] \[=2.15K\] \[\frac{\Delta {{T}_{f2}}}{2.15}=\frac{342}{180}\] \[\Delta {{T}_{f2}}=4.085K\] So, freezing point of glucose in water \[=273.15-4.085=269.05\text{ }K\]


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