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BCECE Medical BCECE Medical Solved Papers-2013

  • question_answer
    A quantity of electrical charge that brings about the deposition of 4.5 g Al from \[A{{l}^{3+}}\] at the cathode will also produce the following volume at (STP) of \[{{H}_{2}}(g)\]) from \[{{H}^{+}}\] at the cathode

    A)  44.8 L               

    B)  22.4 L

    C)  11.2L               

    D)  5.6 L

    Correct Answer: D

    Solution :

    \[2{{H}^{+}}+2{{e}^{-}}\xrightarrow{{}}{{H}_{2}}\] \[A{{l}^{3+}}+3{{e}^{-}}\xrightarrow{{}}\,Al\]                 \[\frac{w({{H}_{2}})}{w(A)}=\frac{E({{H}_{2}})}{E\,(Al)}\]                 \[=\frac{1}{9}\]                 \[w({{H}_{2}})=4.5\times \frac{1}{9}\]                 \[=0.5\,\,g\]                 \[=\frac{1}{4}\,\,mol\,{{H}_{2}}\]                 \[=\frac{22.4}{4}=5.6\,L\,{{H}_{2}}\] at \[STP\]


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