JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2008

  • 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,                 \[\frac{{{W}_{(Glu\cos e)}}\times 18}{50\times 180}=\frac{{{W}_{(urea)}}\times 18}{50\times 60}\] \[{{W}_{(Glu\cos e)}}=weight\,of\,glu\cos e\] \[{{W}_{(Glu\cos e)}}=weight\,of\,urea\] Or           \[\frac{{{W}_{(Glu\cos e)}}\times 18}{50\times 180}=\frac{1\times 18}{50\times 60}\]                 \[{{W}_{(Glu\cos e)}}=3\]


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