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VMMC VMMC Medical Solved Paper-2015

  • question_answer
    In the extraction of metals from their ores, which one of the following reduction methods can bring about a non-spontaneous reduction?

    A) Electrolytic reduction

    B) Reduction by carbon

    C) Reduction by another metal

    D) Reduction by hydrogen

    Correct Answer: B

    Solution :

    Reduction of metal by method (a), (c) and (d) will depend on the reduction potential of metal, so cannot bring about a non-spontaneous reduction (for which                                                                                            \[\Delta G=+ve\] ). In case of carbon reduction net                                                                                                 \[\Delta G\] of overall reaction (reduction of metal and oxidation of carbon) can be made negative (i.e. spontaneous) at high temperature because entropy change \[(\Delta S)\] while oxidation of carbon is positive.


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