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NEET Chemistry The d-and f-Block Elements / d तथा f ब्लॉक के तत्व Question Bank Self Evaluation Test - The d-and f-Block Elements

  • question_answer
    A red solid is insoluble in water. However it becomes soluble if some KI is added to water. Heating the red solid in a test tube results in liberation of some violet coloured fumes and droplets of a metal appear on the cooler parts of the test tube. The red solid is

    A) \[Hg{{I}_{2}}\]                        

    B) \[HgO\]

    C) \[P{{b}_{3}}{{O}_{4}}\]                     

    D) \[{{(N{{H}_{4}})}_{2}}C{{r}_{2}}{{O}_{7}}\]

    Correct Answer: A

    Solution :

    [a] When KI is added to mercuric iodide it disssolve in it and form complex. \[\underset{\begin{smallmatrix}  red,\,solid \\  (insoluble) \end{smallmatrix}}{\mathop{Hg{{I}_{2}}}}\,+KI\to \underset{(soluble)}{\mathop{{{K}_{2}}[Hg{{I}_{4}}]}}\,\] On heating \[Hg{{I}_{2}}\] decomposes as \[Hg{{I}_{2}}\rightleftharpoons Hg+\underset{\left( violet\text{ }vapours \right)}{\mathop{{{I}_{2}}}}\,\]


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