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NEET NEET SOLVED PAPER 2015 (C)

  • question_answer
    In Duma's method for estimation of nitrogen, 0.25g of an organic compound gave 40 mL of nitrogen collected at 300 K temperature and 725 mm pressure. If the aqueous tension at 300 K is 25 mm, the percentage of nitrogen in the compound is                                                                                                                     

    A)  17. 36          

    B)  18.20   

    C)  16.76              

    D)  15.76

    Correct Answer: C

    Solution :

    Experimental values \[{{P}_{{{N}_{2}}}}\,={{P}_{total}}\,-{{P}_{{{H}_{2}}O}}\,=725\,-25\,=700\,\text{mm}\] According to Duma's method for estimation of N, Weight of nitrogen \[=\frac{pVM}{RT}\] where, p is pressure = 700 mm V of nitrogen = 40mL                           M molecular mass of \[{{N}_{2}}=28\] \[R-0.0821\] \[T-300K=\frac{700\times 40\times 28}{760\times 1000\,\times 300\,\times 0.0821}=0.042g\] \[\therefore \] & of nitrogen \[=\frac{0.042}{0.25}\times 100=16.573%\]


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