1]    Define the 3 different radiations emitted by radioactive nuclei.  Include a comparison of their  relative energies and describe  what happens to the nucleus for each decay mode.

 

Answer:   Alpha, Beta, Gamma ;  see text for descriptions!

 

 

5]         The atomic mass of the isotope   105B   is  10.012938 u (this includes the electrons, donít forget  them).   What is the binding energy per nucleon for this isotope?

 

Answer:  6.475  MeV/nucleon

 

 

1]       A possible step in the fusion reactions for the Sun has a hydrogen nucleus (1.00728 u)  fusing with a 7Be nucleus ( 7.01470 u ) to form a Boron nucleus ( 8B, 8.02186 u ) with the emission of a gamma ray.  Write out the nuclear reaction equation for this process and determine the maximum energy (in MeV) of that gamma ray?

 

Answer:      

11H       +        74Be                 -------           85B        +    00gamma


                                                      
0.11  MeV

 


Multiple Choice



1.   The advantage of a fusion reactor  when  compared to a fission reactor  is which of the following?


    A.  the fuel is cheaper

    B.  there would be much less radioactive waste material

    C.   it takes less energy to cause fusion than it does fission.

    D.   both choice A and  B are valid



2.    Which particle below is the least stable (ie. can decay ) over time?


      A.   proton
      B.   neutron
      C.  electron
      D.  photon


3.  Uranium-238 decays into the element Thorium-234.  Which of the following must be emitted in this one decay process?


A.  gamma ray
B.  beta  particle
C.  alpha particle
D.  positron
E.   neutron


4.  Approximately how many half-life periods would have to elapse if the activity of a radioactive isotope sample is to be reduced to 1/60  of its original value?


A.  2
B.  4
C.  6

D.  12
E.  16





Answers:
1. d
2. b
3. c
4. c