JEE Main & Advanced Physics Kinetic Theory of Gases JEE PYQ-Kinetic Theory Of Gases

  • question_answer
    A \[25\times {{10}^{-3}}{{m}^{3}}\]volume cylinder is filled with 1 mol of \[{{O}_{2}}\]gas at room temperature (300K). The molecular diameter of \[{{O}_{2}}\], and its root mean square speed, are found to be 0.3 nm, and 200 m/s, respectively. What is the average collision rate (per second) for an \[{{O}_{2}}\] molecule? [JEE Main 10-4-2019 Morning]

    A) \[\tilde{\ }{{10}^{11}}\]          

    B)      \[\tilde{\ }{{10}^{13}}\]

    C) \[\tilde{\ }{{10}^{10}}\]          

    D)      \[\tilde{\ }{{10}^{12}}\]

    Correct Answer: D

    Solution :

    [d]\[\text{v}=\frac{{{V}_{a\text{v}}}}{\lambda }\]                   
    \[\lambda =\frac{RT}{\sqrt{2}\pi {{\sigma }^{2}}{{N}_{A}}P}\]
    \[P=\frac{RT}{V}\]
    \[\Rightarrow \lambda =\frac{V}{\sqrt{2}\pi {{\sigma }^{2}}{{N}_{A}}}\]
    \[{{V}_{a\text{v}}}=\sqrt{\frac{8}{3\pi }}\times {{V}_{rms}}\]
    \[\therefore \text{v}=\frac{200\times \sqrt{2}\pi \times {{\sigma }^{2}}{{N}_{A}}}{25\times {{10}^{-3}}}\times \sqrt{\frac{8}{3\pi }}\]
    \[=17.68\times {{10}^{8}}/\sec .\]
    \[=.1768\times {{10}^{10}}/\sec \tilde{\ }{{10}^{10}}\]         
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