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JEE Main & Advanced Chemistry Surface & Nuclear Chemistry / भूतल और नाभिकीय रसायन Question Bank Colloids Emulsion, Gel and Their properties with application

  • question_answer
    On addition of one ml solution of \[10%NaCl\] to 10 ml gold sol in the presence of 0.25 gm of starch, the coagulation is just prevented. Starch has the following gold number [MP PET/PMT 1988]

    A)                 0.025    

    B)                 0.25

    C)                 0.5         

    D)                 250

    Correct Answer: D

    Solution :

                    By definition gold number of starch is the amount of starch in mg added to 10 ml standard gold sol which prevents the coagulation of gold on adding 1 ml  of 10% NaCl solution. So the amount of starch is 0.25g = 250 mg. Hence gold number is 250.


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