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NEET Sample Paper NEET Sample Test Paper-55

  • question_answer
    A layer of 0.25 mm thick chromium metal is to be electroplated on the rims of autovehicle with a total area of \[32\text{ }{{m}^{2}}\] from a solution of\[CrO_{4}^{2-}\]. What amount of electric current is required for electroplating the rims in 60 sec? The density of  chromium metal is 7.2 g/cc - [At. wt. of \[Cr=52\]]

    A) \[4.9\,\,\times \,\,{{10}^{3}}\,amp\]      

    B) \[1.78\times {{10}^{3}}\,amp\]

    C) \[5.3\times {{10}^{4}}\,amp\]  

    D) \[10.69\times {{10}^{6}}\,amp\]

    Correct Answer: D

    Solution :

    \[Volume\text{ }of\text{ }coating\text{ }=\text{ }Area\,\,\times \,\,thickness\] \[=\text{ }32\,\,\times \,\,{{10}^{4}}\times \,\,0.025\] \[=\text{ }8000\text{ }c{{m}^{3}}\] \[mass=volume\text{ }\times \text{ }density\] \[=\text{ }8000\,\,\times \,\,7.2\] \[=\text{ }57600\text{ }gm\] \[w=\frac{ItE}{96500}\] \[57600\,\,=\,\,\frac{I\times 60\times (52/6)}{96500}\] \[I\,\,=\,\,10.69\,\,\times {{10}^{6}}\,Amp\]


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