CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2006

  • question_answer
    The mass of glucose that should be dissolved in 50 g of water in order to produce the same lowering of vapour pressure as is produced by dissolving 1 g of urea in the same quantity of water is :

    A)  1 g                                        

    B)  3 g

    C)  6 g                                        

    D)  18 g

    Correct Answer: B

    Solution :

    \[\frac{P-{{P}_{s}}}{P}=\frac{{{w}_{1}}{{M}_{2}}}{{{w}_{2}}{{M}_{1}}}\] To produce same lowering of vapour pressure, \[\frac{P-{{P}_{s}}}{P}\] will be same for both cases. So,                 \[\frac{{{W}_{(Glucose)}}\times 18}{50\times 18}=\frac{{{W}_{(urea)}}\times 18}{50\times 60}\]                 \[{{W}_{(Glucose)}}\]= weight of glucose                 \[{{W}_{(Glucose)}}\]= weight of urea                 \[\frac{{{W}_{(Glucose)}}\times 18}{50\times 18}=\frac{1\times 18}{50\times 60}\]                                 \[{{W}_{(Glucose)}}=3\]


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