JEE Main & Advanced JEE Main Paper (Held On 12 May 2012)

  • question_answer
    In the electrolysis of alumina to obtain aluminium metal, cryolite is added mainly to     JEE Main Online Paper (Held On 12 May 2012)

    A) lower the melting point of alumina

    B)                        dissolve alumina in molten cryolite

    C)                        remove the impurities of alumina

    D)                        increase the electrical conductivity

    Correct Answer: A

    Solution :

                    Fused alumina \[(A{{l}_{2}}{{O}_{3}})\] is a bad conductor of electricity Therefore, cryolite \[(N{{a}_{3}}Al{{F}_{6}})\]and fluorspar \[(Ca{{F}_{2}})\] are added to purified alumina which not only make alumina a good conductor of electricity but also reduce the melting point of the mixture to around 1140K.


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