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KVPY Sample Paper KVPY Stream-SX Model Paper-13

  • question_answer
    The cyanide process of gold extraction involves leaching out gold from its ore with \[\text{C}{{\text{N}}^{-}}\] in the presence of Q in water to form R. Subsequently R is treated with T to obtain Au and Z. Choose the correct option(s):

    A) Z is \[{{[\text{Zn}{{(\text{CN})}_{4}}]}^{2\,-}}\]

    B) R is \[[\text{Au}{{(\text{CN})}_{4}}]{{\,}^{-}}\]

    C) T is Zn

    D) \[\text{Q}\,\text{is}\,{{\text{O}}_{2}}\]

    Correct Answer: A , C , D

    Solution :

    (i) \[Au+\underset{+{{H}_{2}}O}{\mathop{C{{N}^{-}}}}\,+\underset{''Q''}{\mathop{{{O}_{2}}}}\,\to \,{{\underset{''R''}{\mathop{(Au{{(CN)}_{2}})}}\,}^{-}}+O{{H}^{-}}\] (ii) \[{{\underset{''R''}{\mathop{[Au{{(CN)}_{2}}]}}\,}^{-}}+\underset{''T''}{\mathop{Zn}}\,\to \underset{''Z''}{\mathop{{{[Zn{{(CN)}_{4}}]}^{2\,-}}}}\,\,+\,Au\]

    Solution :

    Same as above

    Solution :

    Same as above


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