NEET Sample Paper NEET Sample Test Paper-11

  • question_answer
    In Duma's method for estimation of nitrogen. 0.25 g 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)  16.76                          

    B)  15.76

    C)  17.36                          

    D)  18.20

    Correct Answer: A

    Solution :

    Mass of organic compound = 0.25 g Experimental values At STP \[{{V}_{1}}=40\,mL\]   \[{{V}_{2}}=?\] \[{{T}_{1}}=300K\]      \[{{T}_{2}}=273\,K\] \[{{P}_{1}}=725-25=700\,mm\]            \[{{P}_{2}}=760\,mm\] \[\frac{{{P}_{1}}{{V}_{1}}}{{{T}_{1}}}=\frac{{{P}_{2}}{{V}_{2}}}{{{T}_{2}}}\] \[{{V}_{2}}=\frac{{{P}_{1}}{{V}_{1}}{{T}_{2}}}{{{T}_{1}}{{P}_{2}}}=\frac{700\times 40\times 273}{300\times 760}=33.52\,mL\] 22400 mL of \[{{N}_{2}}\]at STP weights = 28 g \[\therefore \]33.52 mL of \[{{N}_{2}}\] at STP weighs \[=\frac{28\times 33.52}{22400}=0.0419g\]         % of \[N=\frac{\text{Mass}\,\text{of}\,\text{nitrogen}\,\text{at}\,\text{STP}}{\text{Mass}\,\text{of}\,\text{organic}\,\text{compound}\,\text{taken}}\times 100\] \[=\frac{0.0419}{0.25}\times 100=16.76%.\]


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