8th Class Science Chemical Effects of Electric Current Question Bank Chemical Effects of Electric Current

  • question_answer
    Direction: Four substances were tested for their electrical conductivity. The results are shown in the table. Study the table and answer the following questions.
    Substance Bulb Substance at Cathode Substance at Anode
    P Lights up Aluminium Oxygen
    Q Lights up Nothing Nothing
    R Does not light up Nothing Nothing
    S Lights up Hydrogen Carbon dioxide
    Which solutions could be alumina and magnesium nitrate respectively?

    A)  P and Q

    B)  R and Q

    C)  P and S

    D)  P is the alumina but no one is magnesium nitrate.

    Correct Answer: D

    Solution :

    When electricity is passed through molten alumina during electrolysis, the alumina splits up into its elements aluminium and oxygen. In the electrolysis of magnesium nitrate, oxygen is formed at anode and hydrogen is formed at cathode.


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