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NEET Sample Paper NEET Sample Test Paper-4

  • question_answer
    The molar conductivity at infinite dilution of \[A{{l}_{2}}\,{{(S{{O}_{4}})}_{3}}\] is\[858\text{ }S\text{ }c{{m}^{2}}\text{ }mo{{l}^{-1}}\]. Calculate the molar ionic conductivity of \[A{{l}^{3+}}\] ion given that \[{{\wedge }^{o}}\,\left( SO_{4}^{2-} \right)\]\[=160\,c{{m}^{2}}\,mo{{l}^{-1}}\]..

    A)  289                            

    B)  89

    C)  345                            

    D)  189

    Correct Answer: D

    Solution :

    According to Kohlrausch's law \[{{\wedge }^{o}}\left( SO_{4}^{2-} \right)=160\,S\,\,c{{m}^{2}}\,\,mo{{l}^{-1}}\] \[{{\wedge }^{o}}\left[ A{{l}_{2}}{{(S{{O}_{4}})}_{3}} \right]\,2\,{{\wedge }^{o}}\,\left( A{{l}^{3+}} \right)+3{{\wedge }^{o}}\left( SO_{4}^{2-} \right)\] \[{{\wedge }^{o}}\left[ A{{l}_{2}}{{(S{{O}_{4}})}_{3}} \right]\,=858\,S\,c{{m}^{2}}\,mo{{l}^{-1}}\] \[858=2{{\wedge }^{o}}\left( A{{l}^{3+}} \right)+3\times 160\] \[{{\wedge }^{o}}\left( A{{l}^{3+}} \right)=\frac{858-480}{2}=189\,S\,c{{m}^{2}}\,mo{{l}^{-1}}\]


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