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WB JEE Medical WB JEE Medical Solved Paper-2015

  • question_answer
    Extraction of gold (Au) involves the formation of complex ions X and Y. Gold ore \[\xrightarrow[C{{N}^{-}}.{{H}_{2}}O.{{O}_{2}}]{Roasting}H{{O}^{-}}+X\xrightarrow{Zn}Y+Au\] X and y respectively are

    A)  \[Au(CN)_{2}^{-}\]and \[Zn(CN)_{4}^{2-}\]

    B)  \[Au(CN)_{4}^{3-}\]and\[Zn(CN)_{4}^{2-}\]

    C)  \[Au(CN)_{3}^{-}\]and \[Zn(CN)_{6}^{4-}\]

    D) \[Au(CN)_{4}^{-}\] and \[Zn(CN)_{3}^{-}\]

    Correct Answer: A

    Solution :

     Extraction of gold (Au) involves the following sequence of reaction, Gold ore\[\xrightarrow[C{{N}^{-}},{{H}_{2}}O,{{O}_{2}}]{Roasting}H{{O}^{-}}+\underset{X}{\mathop{Au(CN)_{2}^{-}}}\,\] \[\xrightarrow{Zn}\underset{Y}{\mathop{Zn(CN)_{4}^{2-}}}\,+Au\] Hence, \[X=Au(CN)_{2}^{-},Y=Zn(CN)_{4}^{2-}\]


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