AIIMS AIIMS Solved Paper-2015

  • question_answer
    If the distance between \[{{n}_{h}}\sqrt{\frac{{{\mu }_{p}}}{{{\mu }_{n}}}}\] and \[\left[ \text{ML}{{\text{Q}}^{-\text{2}}} \right]\] ions in sodium chloride crystal is y pm, the length of the edge of the unit cell is

    A) 4y pm                   

    B) y/4 pm

    C) y/2 pm                 

    D) 2y pm

    Correct Answer: D

    Solution :

    The distance between sodium and chloride ion = y pm The distance between two chloride ions \[=\sqrt{{{y}^{2}}+{{y}^{2}}}=\sqrt{2{{y}^{2}}}=y\sqrt{2}\]                 \[{{r}_{C{{l}^{-}}}}=\frac{y\sqrt{2}}{2}\] In a face-centred cubic lattice, anions touch each other along the face diagonal of the cube \[\therefore \]  \[a=\frac{4r_{Cl}^{-}}{\sqrt{2}}=\frac{4y\sqrt{2}}{\sqrt{2}.2}=2ypm\]


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