Multiple Choice
Estimate the half-life of the isotope from the graph below.
21. Nuclear Chemistry
Rate of Radioactive Decay
Back21. Nuclear Chemistry
Rate of Radioactive Decay
- Multiple ChoiceHow long will it take for 80% of a 1.20-mg sample of Rn-220 to decay? The half-life of Rn-220 is 55.6 s.
- Multiple ChoiceA sample of Th-219 requires 3.84 × 10−6 seconds to decay to 1.50 mg. What was the initial mass of the sample of Th-219? (t1/2 for Th-219 = 1.05 × 10−6 s)
- Multiple ChoiceHow many mg of a 3.50-mg sample of Tc-99 will remain after 4 half-lives have passed?
- Multiple Choice
For the radioactive decay of lead-202 the decay constant is 1.32 x 10-5 yr-1. How long will it take in hours to decrease to 53% of its initial amount?
- Multiple Choice
During World War I radium-226 was used in the manufacturing of luminous paint. If it takes 2.12 x 104 days for its degradation to be 2.49% complete, what is its decay constant?
- Multiple Choice
If the decay constant for polonium-209 is 6.80 x 10-3 ys-1, what fraction of it remains after 1.1 x 104 years?
- Open Question
A fossil is found to have a 14c level of 64.0% compared to living organisms. How old is the fossil?
- Open Question
A fossil is found to have a 14C level of 85.0% compared to living organisms. How old is the fossil?
- Multiple ChoiceCarbon-14, which is present in all living tissue, radioactively decays via a first-order process. A one-gram sample of wood taken from a living tree gives a rate for carbon-14 decay of 13.6 counts per minute. If the half-life for carbon-14 is 5720 years, what is the age of a sample that has a decay rate of 6.8 counts per minute?
- Multiple ChoiceThe half-life for the radioactive decay of U-238 is 4.5 billion years and is independent of initial concentration. How long will it take for 20% of the U-238 atoms in a sample of U-238 to decay?