JEE Main & Advanced Physics Nuclear Physics And Radioactivity Question Bank Nucleus, Nuclear Reaction

  • question_answer
    Order of magnitude of density of uranium nucleus is \[({{m}_{p}}=1.67\times {{10}^{-27}}kg)\] [MP PET 1995; IIT-JEE 1999; MP PMT 2000; UPSEAT 2003]

    A)            \[{{10}^{20}}kg/{{m}^{3}}\]   

    B)            \[{{10}^{17}}kg/{{m}^{3}}\]

    C)            \[{{10}^{14}}kg/{{m}^{3}}\]   

    D)            \[{{10}^{11}}kg/{{m}^{3}}\]

    Correct Answer: B

    Solution :

                       The order of magnitude of mass and volume of uranium nucleus will be m ≃ A(1.67 ´ 10-27 kg)                          (A is atomic number) \[V=\frac{4}{3}\pi {{r}^{3}}\tilde{-}\frac{4}{3}\pi \ {{[(1.25\times {{10}^{-15}}m){{A}^{1/3}}]}^{3}}\] \[\tilde{-}(8.2\times {{10}^{-45}}{{m}^{3}})A\] Hence,  \[\rho =\frac{m}{V}=\frac{A(1.67\times {{10}^{-27}}kg)}{(8.2\times {{10}^{-45}}{{m}^{3}})A}\] \[\tilde{-}2.0\times {{10}^{17}}kg/{{m}^{3}}\].


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