1. Chapter 25 Review Solutions

2. Which of the following particles cannot be stopped by metal foil? a. Alphab. Betac. Gamma

3. Which particle of radiation carries the greatest amount of energy? a. Alphab. Betac. Gamma

4. Which particle in the following nuclear reaction is the parent nuclide ?

5. True or False. All nuclear decay reactions are considered transmutation reactions.

6. Which element is used in a nuclear fusion reactor? Hydrogen or Uranium

7. Which variable(s) must be conserved in a nuclear reaction? Mass number The number of protons The number of neutrons The atomic number The type of atoms

8. Which nuclear process is more likely to occur when the mass number is over 60? Fission or Fusion

9. When is positron emission most effective? the neutron to proton ratio is above the band of stability the neutron to proton ratio is below the band of stability

10. When is alpha decay most effective? the neutron to proton ratio is above the band of stability the neutron to proton ratio is below the band of stability

11. When is electron capture most effective? When there is an excess of protons When there is an excess of neutrons

12. What changes in a nuclear equation when a nucleus undergoes beta decay? (choose all) A. Mass number B. Atomic number C. the number of neutrons

13. What is a positron? A positron is a particle that has the mass of a beta particle and a charge of +1

14. What is required to sustain a chain reaction? a. High temperature b. Critical mass c. Water

15. Is Calcium-45 a stable isotope of calcium? Yes or No If your answer is no, what type of decay would it undergo Beta

16. Sodium-20 is an unstable isotope of sodium. What two types of decay might it undergo? Electron capture or positron emission

17. Above what atomic number do most unstable atoms undergo alpha decay? 83

18. Write the induced transmutation reaction for the alpha bombardment of Thorium 230 which produces two neutrons, a beta particle and another nuclide.

19. If the half-life of a radioactive isotope is 12 minutes and 1 hour and 36 minutes passes, how many half-lives have taken place? What fraction of the sample will remain after that time? 1/256

20. If a radioactive isotope decays from 16g to 2g in 15 days, what is the isotope’s half-life? 5 Days

21. How much of a 20g sample of Zn- 65 will remain after 18 years if the half- life of Zn-65 is 6 years? 2.5g

22. What is the daughter nuclide in the following reaction?