NEET Sample Paper NEET Sample Test Paper-31

  • question_answer
    What is the molality of aq. solution of \[{{C}_{2}}{{H}_{5}}OH\] in which mole fraction of \[{{C}_{2}}{{H}_{5}}OH\]is\[0.04\]:-

    A)  \[2.13\text{ }m\]            

    B)  \[0.213\text{ }m\]

    C)  \[41.66\text{ }m\]           

    D)  \[0.041\,\,m\]

    Correct Answer: A

    Solution :

    \[{{X}_{{{C}_{2}}{{H}_{5}}OH}}=0.04\]    \[\therefore \]\[{{X}_{{{H}_{2}}O}}=I-0.04=0.96\] \[\frac{{{X}_{{{C}_{2}}{{H}_{5}}OH}}}{{{X}_{{{H}_{2}}O}}}=\frac{{{n}_{{{C}_{2}}{{H}_{5}}OH}}}{{{n}_{{{H}_{2}}O}}}=\frac{0.04}{0.96}=\frac{1}{24}\] Molality \[=\frac{{{n}_{{{C}_{2}}{{H}_{5}}OH}}}{W(kg)}=\frac{1mol}{\frac{(24\times 18)}{1000}kg}\,\]


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