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KVPY Sample Paper KVPY Stream-SX Model Paper-18

  • question_answer
    Number of \[\alpha \] and \[\beta \text{-}\]particles emitted, when an atom of \[{}_{90}T{{h}^{232}}\] undergoes disintegration to produce an atom of \[{}_{82}P{{b}^{208}},\] are

    A) \[6\alpha \,\text{and}\,\text{4}\beta \]

    B) \[2\alpha \,\text{and}\,\text{4}\beta \]

    C) \[6\alpha \,\text{and}\,2\beta \]

    D) \[4\alpha \,\text{and}\,6\beta \]

    Correct Answer: A

    Solution :

    \[{}_{90}T{{H}^{232}}\xrightarrow{{}}{}_{82}P{{b}^{208}}+x_{2}^{4}\alpha +{{y}_{1}}\beta \]
    Let the number of \[\alpha \]-particles be x.
    Let the number of \[\beta \]-particles be y.
    In radioactive disintegration atomic number as well as mass number must be equal to two sides of equation.
    \[\therefore \]\[208+4x+0y=232\]
    \[4x=24\]
    \[x=6\]
                and       \[82+2x-y=90\]
                            \[2x-y=8\Rightarrow y=4\]
    \[\therefore \]Number of \[\alpha \]-particles = 6
    Number of \[\beta \]-particles = 4.


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