AMU Medical AMU Solved Paper-2001

  • question_answer
    The isotope \[y{{A}^{x}}\] undergoes a series of ma and \[n\beta \] disintegrations to form a stable isotope \[{{y}_{-10}}{{B}^{x-32}}\]. The value of m and n are

    A)  5 and 8                                

    B)  6 and 8

    C)  8 and 6                                

    D)  8 and 10

    Correct Answer: C

    Solution :

                     Key Idea When a nucleus emits an \[\alpha \]-particle\[(_{2}^{4}He)\], the mass number decreases by 4 units and atomic number decreases by 2 units and by the loss of one \[\beta \]-particle atomic number increases by one unit but mass number does not change. The given nuclear charge is \[{{y}^{{{A}^{x}}}}\xrightarrow{{}}{{y}^{-{{10}^{x-32}}}}+{{m}_{2}}H{{e}^{4}}+{{n}_{-1}}{{e}^{0}}\] Here, the loss of mass is by 32 units. So, number of a-particles emitted \[=\frac{32}{8}=8\] By the emission of Sa-particles, the atomic number of the daughter element should become y -16. But it is y -10. Therefore, 6a-particle is also emitted in the nuclear charge. Hence, the value of m and n are 8 and 6 respectively.


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