JEE Main & Advanced Chemistry Structure of Atom / परमाणु संरचना Question Bank Self Evaluation Test - Structure of Atom

  • question_answer
    Two fast moving particles X and Y are associated with de Broglie wavelengths 1 nm and 4 nm respectively. If mass of X is nine times the mass of Y, the ratio of kinetic energies of X and Y would

    A) 3 : 1     

    B) 9 : 1  

    C) 5 : 12   

    D) 16 : 9

    Correct Answer: D

    Solution :

    [d] de Broglie wavelength \[\lambda =\frac{h}{mv}\] \[\frac{{{\lambda }_{1}}}{{{\lambda }_{2}}}=\frac{{{m}_{2}}{{v}_{2}}}{{{m}_{1}}{{v}_{1}}};\frac{1}{4}=\frac{1}{9}\times \frac{{{v}_{2}}}{{{v}_{1}}}\] \[\frac{{{v}_{2}}}{{{v}_{1}}}=\frac{9}{4};\frac{{{v}_{1}}}{{{v}_{2}}}=\frac{4}{9}\] \[KE=\frac{1}{2}m{{v}^{2}}\] \[\frac{K{{E}_{1}}}{K{{E}_{2}}}=\frac{{{m}_{1}}}{{{m}_{2}}}\times \frac{{{v}_{l}}^{2}}{{{v}_{2}}^{2}}=\frac{9}{1}\times {{\left( \frac{4}{9} \right)}^{2}}=\frac{16}{9}\]


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