NEET Sample Paper NEET Sample Test Paper-59

  • question_answer
    An X molal solution of a compound in benzene has mole fraction of solute equal to 0.2. The value of X is nearly:

    A) 14                                

    B) 3.2     

    C) 1.4                               

    D) 2

    Correct Answer: D

    Solution :

    [d] 3.2 \[{{x}_{2}}=\] amount of solute             \[=\frac{{{n}_{2}}}{{{n}_{1}}+{{n}_{2}}}=0.2\] \[\therefore \,{{x}_{1}}=1-0.2=0.8\] \[=\frac{{{n}_{2}}}{{{n}_{1}}+{{n}_{2}}}=0.8\] \[\therefore \frac{{{x}_{2}}}{{{x}_{1}}}=\frac{{{n}_{2}}}{{{n}_{1}}}=\frac{1}{4}\] Taking \[{{n}_{1}}1000/78\]moles (mol. mass of\[{{C}_{6}}{{H}_{6}}=78\])             \[{{n}_{2}}=\frac{1}{4}\times {{n}_{1}}\]                         \[=\frac{1}{4}\times \frac{1000}{78}=3.20\]


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