JCECE Medical JCECE Medical Solved Paper-2013

  • question_answer
    On   adding   0.1M   solution   each   of \[[A{{g}^{+}}],[B{{a}^{2+}}],(C{{a}^{2+}}]\] in\[N{{a}_{2}}S{{O}_{4}}\] solution, species first precipitated is \[[{{K}_{sp}}BaS{{O}_{4}}={{10}^{-11}},{{K}_{sp}}CaS{{O}_{4}}={{10}^{-6}}\]\[and\,{{K}_{sp}}A{{g}_{2}}S{{O}_{4}}={{10}^{-5}}]\]

    A) \[A{{g}_{2}}S{{O}_{4}}\]           

    B) \[BaS{{O}_{4}}\]

    C) \[CaS{{O}_{4}}\]            

    D)  All of these

    Correct Answer: B

    Solution :

     Solubility of\[BaS{{O}_{4}},(x)=\sqrt{{{K}_{sp}}}=\sqrt{{{10}^{-11}}}\] \[=3.16\times {{10}^{-6}}\text{mol}{{\text{L}}^{-1}}\] Solubility of\[CaS{{O}_{4}},\] \[x=\sqrt{{{K}_{sp}}}=\sqrt{{{10}^{-6}}}=1.0\times {{10}^{-3}}\,mol\,{{L}^{-1}}\] Solubility of \[A{{g}_{2}}S{{O}_{4}},x=\sqrt[3]{\frac{{{K}_{sp}}}{4}}\] because for \[A{{g}_{2}}S{{O}_{4}},4{{x}^{3}}={{K}_{sp}}\] \[x=\sqrt[3]{\frac{{{10}^{-5}}}{4}}=1\times {{10}^{-2}}mol\,{{L}^{-1}}\] Least solubility is of BaS04, hence it will precipitate first.


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