KVPY Sample Paper KVPY Stream-SX Model Paper-2

  • question_answer
    1g of charcoal adsorbs \[100\text{ }mL\text{ }0.5\text{ }M\]\[\,C{{H}_{3}}COOH\] to form a monolayer, and thereby the molarity of \[C{{H}_{3}}COOH\] reduces to 0.49.  Calculate the surface area of the charcoal covered by each molecule of acetic acid. Surface area of charcoal \[=3.10\times {{10}^{2}}{{m}^{2}}/g.\]

    A) \[0.5\times {{10}^{-19}}{{m}^{2}}\] 

    B) \[4\times {{10}^{-20}}{{m}^{2}}\]

    C) \[0.5\times {{10}^{-10}}{{m}^{2}}\] 

    D) \[5\times {{10}^{-19}}{{m}^{2}}\]

    Correct Answer: D

    Solution :

    [d]
    Amount of \[C{{H}_{3}}COOH\] adsorbed on Ig of charcoal\[=(0.5-0.49mo1{{L}^{-1}})\]\[\times \frac{100mL}{1000mL/L}=1\times {{10}^{-3}}mol\]
    So, no .of \[C{{H}_{3}}COOH\]molecules in \[1\times {{10}^{-3}}\]mol of acetic acid \[=6.02\times {{10}^{23}}mo{{l}^{-1}}\times {{10}^{-3}}mol=6.02\times {{10}^{20}}\]
    Area occupied by one \[C{{H}_{3}}COOH\] molecule \[=\frac{3.01\times {{10}^{2}}{{m}^{2}}}{6.02\times {{10}^{20}}}=5\times {{10}^{-19}}{{m}^{2}}\]
    Thus the surface area of the charcoal covered by each \[C{{H}_{3}}COOH\]molecule is \[5\times {{10}^{-19}}{{m}^{2}}\]
     


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