KVPY Sample Paper KVPY Stream-SX Model Paper-20

  • question_answer
    Arrange the following in the order of increasing mass (atomic mass:\[0 = 16, Cu= 63, N= 14\])
    I. One atom of oxygen
    II. One atom of nitrogen
    III.\[1\times {{10}^{-10}}\] mole of oxygen
    IV. \[1\times {{10}^{-10}}\]mole of copper

    A) \[II<I<III<IV\]

    B) \[I<II<III<IV\]

    C) \[III<II<IV<I~\]

    D) \[IV<II<III<I\]

    Correct Answer: A

    Solution :

    (I) mass of \[6.023\times {{10}^{23}}\]atoms of oxygen          \[=16g\]
    Mass of one atom of oxygen \[=\frac{16}{6.023\times {{10}^{23}}}=2.66\times {{10}^{-23}}g\]
    (II) Mass of \[6.023\times {{10}^{23}}\]atom of nitrogen \[=14\,g\]
    Mass of one atom of nitrogen\[=\frac{14}{6.023\times {{10}^{23}}}=2.32\times {{10}^{-23}}g\]
    (III) Mass of 1 mole of oxygen =16g
          Mass of \[1\times {{10}^{-10}}\] mole of oxygen \[=16\times {{10}^{-10}}\]
    (IV) Mass of 1 mole of copper=63g
           Mass of \[1\times {{10}^{-10}}\]mole of copper \[=63\times 1\times {{10}^{-10}}=63\times {{10}^{-10}}\]
    So, the order of increasing mass is
    \[\operatorname{II}<I<III<IV.\]


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