J & K CET Medical J & K - CET Medical Solved Paper-2003

  • question_answer
    One of the following metals is obtained by leaching its ore with dilute cyanide solution. Identify it.

    A)  Titanium                            

    B)  Vanadium

    C)  Silver                                   

    D)  Zinc

    Correct Answer: C

    Solution :

                    Silver metal is obtained by Mac-Arthur forest process which is called cyanide process. The concentrated ore of argentite is treated with dilute\[NaCN\]solution and a current of\[{{O}_{2}}\]is continuously passed. Silver sulphide goes into solution in the form of soluble complex sodium argentocyanide. \[2A{{g}_{2}}S+8NaCN+{{O}_{2}}+2{{H}_{2}}O\xrightarrow[{}]{{}}\]                       \[4Na[Ag{{(CN)}_{2}}]+4NaOH+2S\] The soluble complex is treated with zinc dust, when silver gets precipitated. \[2Na[Ag{{(CN)}_{2}}]+Zn\to N{{a}_{2}}[Zn{{(CN)}_{4}}]+2Ag\downarrow \]


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