JEE Main & Advanced Chemistry The Solid State / ठोस प्रावस्था Question Bank Mathematical analysis of cubic system and Bragg's equation

  • question_answer
    How many unit cells are present in a cube-shaped ideal crystal of \[NaCl\] of mass \[1.00\,g\] [Atomic masses: \[Na=23,\,Cl=35.5]\]       [AIEEE 2003]

    A)                 \[2.57\times {{10}^{21}}\] unit cells        

    B)                 \[5.14\times {{10}^{21}}\] unit cells

    C)                 \[1.28\times {{10}^{21}}\] unit cells        

    D)                 \[1.71\times {{10}^{21}}\] unit cells

    Correct Answer: A

    Solution :

           \[\frac{1}{58.5}\times 6.023\times {{10}^{23}}=1.029\times {{10}^{22}}\]            A unit cell contains \[4\,N{{a}^{+}}\]ion and \[4\,C{{l}^{-}}\]ions                                 \Unit cell \[=\frac{1.029\times {{10}^{22}}}{4}\]\[=2.57\times {{10}^{21}}\]unit cell.


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