Nuclear chemistry-radioactive decay

Question

Assignment:

Question 1. A radioisotope decays to give an alpha particle and Pb-208. What was the original element?

• Se
• Bi
• Po
• Hg
• Rn

Question 2. Sulfur-35 decays by beta emission. The decay product is ________.

• P
• S
• Si
• 35-Cl
• 37- Cl

Question 3. Carbon-11 is a radioactive isotope of carbon. Its half-life is 20.3 minutes. What fraction of the initial number of C-11 atoms in a sample will remain after 81 minutes?

• 1/16
• 1/4
• 1/2
• 1/32
• 1/8

Question 4. Po-208 is an alpha emitter with a half-life of 2.90 years. How many mg of polonium from an original sample of 2.0 mg will remain after 8.0 years?

• 0.147 mg
• 0.295 mg
• 0.725 mg
• 6.77 mg
• 1.90 mg

Question 5. Charcoal found under a stone at Stonehenge, England, has a carbon-14 activity that is 0.60 that of new wood. How old is the charcoal? The half-life of carbon-14 is 5,730 years.

• Less than 5,730 years
• Between 5,730 and 11,460 years
• Between 11,460 and 17,190 years
• More than 17,190 years

Question 6. What role does cadmium metal (Cd) play in a nuclear reactor?

• slows down the fission neutrons (moderator)
• transfers heat from the reactor to the heat exchanger (primary coolant)
• controls chain reaction (control rods)
• transfers heat from the condenser to the environment (cooling tower)
• undergoes fission (fuel rods)

Question 7. Which one of the following is the most penetrating of the three types of nuclear radiation?

• alpha
• beta
• gamma

Question 8. Gamma-rays and X-rays cause radiation damage when they interact with matter by producing ________.

• ions and free radicals
• isotopes
• daughter products
• oxidation
• reduction

Question 9. How many neutrons and protons (nucleons) does an atom with the symbol S have?

• 33
• 16
• 49
• 17
• None of the above.

Question 10. Predict the other product of the following nuclear transformation.

Li + n _____ + He