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CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2011

  • question_answer
    1 g of silver gets distributed between \[10\,\,c{{m}^{3}}\]of molten zinc and \[100\,\,c{{m}^{3}}\] of molten lead at\[{{800}^{o}}C\]. The percentage of silver still left in the lead layer is approximately

    A)  2                                            

    B)  5

    C)  3                                            

    D)  1

    Correct Answer: C

    Solution :

    Partition coefficient                 \[=\frac{Conc.\text{ }of\text{ }Agin\text{ }molten\text{ }Zn}{Cone.\text{ }of\text{ }Agin\text{ }molten\text{ }Pb}\] Mass of Ag in lead at equilibrium \[=1-x\] Mass of Ag in Zn at equilibrium \[=x\]                 \[300=\frac{x/10}{1-x/100}=\frac{10x}{1-x}\]                 \[10x=300\,\,(1-x)\]                 \[10x=300-300x\]                                 \[x=\frac{300}{310}\]                                 \[x=\frac{30}{31}\]          Amount of silver in molten lead                 \[=1-x=1-\frac{30}{31}=\frac{31-30}{31}=\frac{1}{31}\] \[\therefore \] % of silver \[=\frac{1}{31}\times 100\simeq 3%\]


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