Modern Physics 5 Question 7

7. A fission reaction is given by 92236U54140Xe+3894Sr+x+y, where x and y are two particles. Considering 92236U to be at rest, the kinetic energies of the products are denoted by KXe, KSr,Kx(2MeV) and Ky(2MeV), respectively. Let the binding energies per nucleon of 92236U,54140Xe and 3894Sr be 7.5 MeV, 8.5 MeV and 8.5 MeV, respectively. Considering different conservation laws, the correct options is/are

(2015 Adv.)

(a) x=n,y=n,KSr=129MeV,KXe=86MeV

(b) x=p,y=e,KSr=129MeV,KXe=86MeV

(c) x=p,y=n,KSr=129MeV,KXe=86MeV

(d) x=n,y=n,KSr=86MeV,KXe=129MeV

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Answer:

Correct Answer: 7. (c)

Solution:

  1. From conservation laws of mass number and atomic number, we can say that x=n,y=n

(x=01n,y=01n)

Only (a) and (d) options may be correct.

From conservation of momentum, |Pxe|=|Psr|

 From K=P22mK1mKSrKxe=mxemSrKSr=129MeV,Kxe=86MeV

NOTE There is no need of finding total energy released in the process.



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