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Chemistry LibreTexts

HW Solutions #10

1. How is nuclear fission different from nuclear fusion?  Why are both of these nuclear processes exothermic?

2. Plutonium-238 is potential source for heart pacemaker batteries with a 87.74 year half-life.  Calculate the activity in units of curies for 0.50 g of pure plutonium-238 used is a pacemaker battery.  Why is Plutonium-238 a good power source in a pacemaker?

3. What is the age of mummified primate skin that contains 4.125% of the original quantity of 14C?

4.  Radioactive Rn-222 is known to accumulate in basement of buildings and constitute a health risk.


  1. What is the parent primary natural radionuclide the produces the Rn-222?


  2. Write the reaction for the nuclear decay of radon-222.


  3. Why are none of the intermediate radionuclides and the parent radionuclide considered a health risk?

5. Cobalt-60 has a half-life of 5.26 yr. The cobalt-60 in a radiotherapy unit must be replaced when its radioactivity falls 75% of the original sample. If the original sample was purchased in July 2008, when should you replace the cobalt-60 sample?

6. What is the difference between electrons and β- particles?

7. Write the nuclear reactions for the following:

  1. the α decay of 238Pu        
  2. the negatron (negative beta particle) decay of 60Co


  3. the positron decay of 11C            
  4. the electron capture decay of 208Bi


  5. the neutron-induced fisson of 235U into 144Ba, γ and two neutrons

8. Write the balanced equation for the beta decay of 14C.

  1. 146C → 147N + 0-1e- + ν

9. Write the balanced equation for the positron emission decay of 22Na.

  1. 2211Na → 2210Ne + 0+1e+ + ν

10. Write the balanced equation for electron capture in 207Bi.

  1. 20783Bi + 0-1e-20782Pb + ν

11. Write the balanced equation for the alpha decay of 238U.

  1. 23892U → 23490Th + 42He