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

  • question_answer
    In a normal spinel type structure, the oxide ions are arranged in ccp whereas 1/8 tetrahedral holes are occupied by \[Z{{n}^{2+}}\] ions and 50% of octahedral holes are occupied by \[F{{e}^{3+}}\] ions .The formula of the compound is

    A) \[Z{{n}_{2}}F{{e}_{2}}{{O}_{4}}\]

    B) \[ZnF{{e}_{2}}{{O}_{3}}\]

    C) \[ZnF{{e}_{2}}{{O}_{4}}\]  

    D) \[ZnF{{e}_{2}}{{O}_{2}}\]

    Correct Answer: C

    Solution :

    [c] Number of O-atoms per unit cell \[=\frac{1}{8}\times 8+\frac{1}{2}\times 6=4\] Number of octahedral holes per unit cell \[=1\times 4=4\] Number of \[F{{e}^{3+}}\]ions per unit cell \[=\frac{50\times 4}{100}=2\] Number of tetrahedral voids per unit cell \[=2\times 4=8.\] Number of \[Z{{n}^{2+}}\] ions per unit cell \[=\frac{1}{8}\times 8=1\] Hence, formula: \[ZnF{{e}_{2}}{{O}_{4}}\]


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