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CET Karnataka Medical CET - Karnataka Medical Solved Paper-2014

  • question_answer
    \[1.78g\]of an optically active L-amino acid  is treated with \[NaN{{O}_{2}}/HCl\]at \[{{0}^{o}}C\]. \[448\text{ }c{{m}^{3}}\] of nitrogen gas at STP is evolved. A sample of protein has \[0.25%\]of this amino acid by mass. The molar mass of the protein is

    A)  \[36,500g\text{ }mo{{l}^{-1}}\]

    B)  \[34,500g\text{ }mo{{l}^{-1}}\]

    C)  \[35,400g\text{ }mo{{l}^{-1}}\]

    D)  \[35,600g\text{ }mo{{l}^{-1}}\]

    Correct Answer: D

    Solution :

    : \[L-\text{amino acid}\,\xrightarrow[{{0}^{o}}C]{NaN{{O}_{2}}+HCl}{{N}_{2}}\uparrow \] 1 mole of L-amino acid \[\to \] 1 mole of \[{{N}_{2}}\]      \[=22400c{{m}^{3}}\]of \[{{N}_{2}}\] at STP \[448c{{m}^{3}}\] of  \[{{N}_{2}}\equiv 1.78g\] of L-amino acid \[22,400\text{ }c{{m}^{3}}\]of \[{{N}_{2}}\equiv xg\]of L-amino acid Sample of protein has 0.25% amino acid.
    Amino acid Protein
    \[0.25\] \[100\]
    \[89\] \[y\]
    \[y=\frac{89\times 100}{0.25}=35,600g/mol\]


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