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CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2001

  • question_answer
    Aluminium displaces hydrogen from acids, but copper does not. A Galvanic cell prepared by combining \[\text{Cu/C}{{\text{u}}^{\text{2}}}\text{+}\]and \[\text{Al/A}{{\text{l}}^{\text{3+}}}\]has an emf of\[\text{2}\text{.0 V}\] at\[\text{298 K}\text{.}\]If the potential of copper electrode is\[\text{+ 0}\text{.34 V,}\] that of aluminium electrode is:

    A) \[-\,2.3V\]                          

    B) \[+\,2.34V\]

    C) \[-1.66\,V\]                       

    D) \[+\,1.66\,V\]

    Correct Answer: C

    Solution :

    \[\because \]\[{{E}_{RHE}}=Cu/C{{u}^{2+}}\] \[{{E}_{LHE}}=Al/A{{l}^{3+}}\] We know that \[{{E}_{cell}}={{E}_{RHE}}-{{E}_{LHE}}\]                                 \[2=+\,0.34-x\] \[\therefore \]  \[x=+0.34-2=-1.66\,V\]


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