15. Chemical Kinetics

How much of a radioactive parent isotope will remain after three half-lives have passed?

If a sample initially contains 1.0 × 10^{12} atoms of the cadmium isotope 109Cd, which has a half-life of 462 days, approximately how many atoms of 109Cd will remain after 924 days?

Which of the following is the correct formula for calculating the age of a meteorite using half-life?

A radioactive isotope decays such that after 24 hours, only 25% of the original sample remains. What is the half-life of this isotope?

Which of the following best describes the possible range of half-lives for radioactive isotopes?

After 5 half-lives have passed for 87Rb, what percentage of daughter isotopes would be present?

If the decay constant for element X is 6.931 yr^{-1}, what is its half-life?

Iodine-131 has a half-life of 8.0 minutes. How many half-lives will pass in 120 minutes?

Which statement accurately describes a half-life?

The half-life of bromine-74 is 25 min. How much of a 4.0 mg sample remains after 75 min?

After two half-lives, what fraction of a radioactive sample remains undecayed?

After a radioactive sample undergoes two half-lives, what fraction of the original sample remains?

If a radioactive sample is in its second half-life, what percentage of the original sample remains undecayed (stable) at this point?

After four half-lives, what fraction of a sample's original radioactive atoms remains?

Given the rate law rate = 1301 min^{-1} [A] for a particular reaction, what is the half-life (t_{1/2}) for this reaction?