NEET Chemistry The Solid State / ठोस प्रावस्था Question Bank Self Evaluation Test - The Solid State

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

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

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

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

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

    Correct Answer: D

    Solution :

    [d] Since in \[NaCl\] type of structure 4 formula units form a cell. 58.5 gm. Of \[NaCl=6.023\times {{10}^{23}}\]atoms 1 gm of atoms \[NaCl=\frac{6.023\times {{10}^{23}}}{58.5}\] 4 atoms constitute 1 unit cell \[\therefore =\frac{6.023\times {{10}^{23}}}{58.5}\] atoms constitute \[=\frac{6.023\times {{10}^{23}}}{58.5\times 4}\] \[=2.57\times {{10}^{21}}\] unit cells.


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