Atoms And Nuclei Question 405

Question: A nucleus at rest undergoes a decay emitting an α particle of de-Broglie wavelength λ=5.76×1015m. If the mass of the daughter nucleus is 223.610 amu and that of the α particle is 4.002,amu, determine the mass of the parent nucleus inamu. (1,amu=931.470MeV/c2].

Options:

A) 227.62amu

B) 112.11amu

C) 90.3amu

D) 23.8amu

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Answer:

Correct Answer: A

Solution:

  • By conservation of momentum, we have

    0=Pα+PdPα=Pd

    or Pα=Pd=P The kinetic energy released in the process K=Kα+Kp=P22mα+P22md =P22mα(1+mαmd)=(h/λ)22mα(1+mαmd)

    After substituting the given values, we get K=6.25MeV

    If mP is the mass of the parent nucleus, then K+(mα+md)c2=mpc2 or 6.25+(223.61+4.002)c2=mpc2

    After simplifying, we get mp=227.62 amu.



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