NEET AIPMT SOLVED PAPER SCREENING 2012

  • question_answer
    Aluminium is extracted from alumina \[(A{{l}_{2}}{{O}_{3}})\] by electrolysis of a molten mixture of

    A) \[A{{l}_{2}}{{O}_{3}}+HF+NaAl{{F}_{4}}\]

    B) \[A{{l}_{2}}{{O}_{3}}+Ca{{F}_{2}}+NaAl{{F}_{4}}\]

    C) \[A{{l}_{2}}{{O}_{3}}+N{{a}_{3}}Al{{F}_{6}}+Ca{{F}_{2}}\]

    D) \[A{{l}_{2}}{{O}_{3}}+KF+N{{a}_{3}}Al{{F}_{6}}\]

    Correct Answer: C

    Solution :

    Alumina, \[A{{l}_{2}}{{O}_{3}},\], is a bad conductor of electricity and has very high melting point, so before subjecting to electrolysis, it is mixed with fluorspar \[(Ca{{F}_{2}})\] and cryolite \[(N{{a}_{3}}Al{{F}_{6}})\], which lower its melting point and make it more conducting.


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