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JEE Main & Advanced Sample Paper JEE Main Sample Paper-32

  • question_answer
    \[Zn\] Amalgam is prepared by electrolysis of aqueous \[ZnC{{l}_{2}}\] using Hg cathode (9gm). How much current is to be passed through \[ZnC{{l}_{2}}\] solution for 1000 seconds to prepare a Zn Amalgam with 25% Zn by wt.(Zn=65.4)

    A) 5.6 amp      

    B)                    7.2 amp

    C) 8.85 any        

    D)    11.2 amp

    Correct Answer: C

    Solution :

    Lex x gm of Zn deposite on 9 gm of Hg % of Zn in Amalgam \[=\frac{{{m}_{zn}}\,\times 100}{{{m}_{Zn}}+\,{{m}_{Hg}}}\,\,=\frac{x}{9+x}\,\times 100\,=25\] \[\therefore \,\,\,\,\,\,\,\,\,\,\,x=3gm\] \[Eq.\,of\,Zn\,=\frac{3\times 2}{65.4}\] \[\frac{{{n}_{Zn}}}{1}\,=\frac{{{n}_{{{e}^{-}}}}}{2}\,=\frac{Q}{2f}=\frac{it}{2f}\] Current \[i=\frac{6}{65.4}\,\times \,\frac{96500}{1000}\,=8.85\,amp\].


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