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KVPY Sample Paper KVPY Stream-SX Model Paper-22

  • question_answer
    Two Faraday of electricity is passed through a solution of \[CuS{{O}_{4}}.\] The mass of copper deposited at the cathode is (at. mass of \[Cu=63.5\text{ }u\])

    A) 0 g

    B) 63.5 g

    C) 2 g

    D) 127 g

    Correct Answer: B

    Solution :

    According to Faraday's second law
    Given, \[Q=2F\]Atomic mass of \[Cu=63.5u\]
    Valency of the metal \[Z=2\]
    We have, \[CuS{{O}_{4}}\to C{{u}^{2+}}+S{{O}^{2-}}_{4}\]
    \[\underset{1mol}{\mathop{C{{u}^{2+}}}}\,+\underset{\begin{smallmatrix}  2mol \\  2F \end{smallmatrix}}{\mathop{2{{e}^{-}}}}\,\to \underset{1mol=63.5g}{\mathop{Cu}}\,\]
    Alternatively. \[W=ZQ=\frac{E}{F}.2F=2E=\frac{2\times 63.5}{2}=63.5g\]


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