DUMET Medical DUMET Medical Solved Paper-2004

  • question_answer
    The solubility product of \[A{{g}_{2}}Cr{{O}_{4}}\] is\[32\times {{10}^{-12}}\]. What is the concentration of \[CrO_{4}^{2-}\] ions in that solution (in g ions \[{{L}^{-1}}\])?

    A)  \[2\times {{10}^{-4}}\]

    B)  \[8\times {{10}^{-4}}\]

    C)  \[8\times {{10}^{-8}}\]

    D)  \[16\times {{10}^{-4}}\]

    Correct Answer: A

    Solution :

    Key Idea: First find relationship between solubility product and solubility after writing dissociation reaction of\[A{{g}_{2}}Cr{{O}_{4}}\]. Then substitute the given values to find the answer. Let the solubility of \[A{{g}_{2}}Cr{{O}_{4}}=x\,g/L\] \[A{{g}_{2}}Cr{{O}_{4}}\to 2A{{g}^{+}}+C{{r}_{2}}O_{4}^{2-}\] Conc. \[x\]       \[2x\] \[x\] \[{{K}_{sp}}=[A{{g}^{2+}}][Cr{{O}_{4}}^{2-}]\] \[={{(2x)}^{2}}(x)\] or \[{{K}_{sp}}=4{{x}^{3}}\] \[\therefore \] \[x=\sqrt[3]{\frac{{{K}_{sp}}}{4}}\] Given, \[{{K}_{sp}}=32\times {{10}^{-12}}\] \[\therefore \] \[x=\sqrt[3]{\frac{32\times {{10}^{-12}}}{4}}\]


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