RAJASTHAN ­ PET Rajasthan PET Solved Paper-2007

  • question_answer
    The mass of two molecules A and B are 100 kg and 64 kg respectively. If the diffusion rate of A is\[12\times {{10}^{-3}}\]then, the diffusion rate of B will be

    A)  \[15\times {{10}^{-3}}\]         

    B)  \[64\times {{10}^{-3}}\]

    C)  \[5\times {{10}^{-3}}\]        

    D)  \[46\times {{10}^{-3}}\]

    Correct Answer: A

    Solution :

     According to Graham's law of diffusion: \[\frac{{{r}_{A}}}{{{r}_{B}}}=\sqrt{\frac{{{M}_{B}}}{{{M}_{A}}}}\] \[{{M}_{A}}=\frac{100}{2}kg/mol\] \[{{M}_{B}}=\frac{64}{2}kg/mol\] and \[{{r}_{A}}=12\times {{10}^{-3}}\] \[{{r}_{B}}=?\] \[\frac{{{r}_{A}}}{{{r}_{B}}}=\sqrt{\frac{{{M}_{B}}}{{{M}_{A}}}}\] \[\therefore \] \[\frac{12\times {{10}^{-3}}}{{{r}_{B}}}=\sqrt{\frac{64/2}{100/2}}\] \[\frac{12\times {{10}^{-3}}}{{{r}_{B}}}=\frac{8}{10}\] \[{{r}_{B}}=\frac{12\times {{10}^{-3}}\times 10}{8}\] \[=15\times {{10}^{-3}}\]


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