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Punjab Medical Punjab - MET Solved Paper-2010

  • question_answer
    An electron tube was sealed-off during manufacture at a pressure of \[1.2\times {{10}^{-7}}mm\] of mercury at\[{{27}^{o}}C\]. Its volume is \[100c{{m}^{3}}\]. The number of molecules that remain in the tube is

    A) \[2\times {{10}^{16}}\]                 

    B) \[3\times {{10}^{15}}\]

    C) \[3.86\times {{10}^{11}}\]                           

    D) \[5\times {{10}^{11}}\]

    Correct Answer: C

    Solution :

    \[pV=nRT\]\[\Rightarrow \]\[(1.2\times {{10}^{-10}}\times 13.6\times {{10}^{3}}\times 9.8)\times {{10}^{-4}}\]\[=n\times 8.31\times (273+27)\] \[\therefore \]Number of moles\[n=6.42\times {{10}^{-13}}\] Hence, number of molecules\[=6.42\times {{10}^{-13}}\times 6.02\times {{10}^{23}}=3.86\times {{10}^{11}}\]


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