IB Physics Radioactive decay

A tutorial sheet on radioactive decay in Topic E follows.

  1. Choose the best definition of half-life. (a) The time taken for one-half of the initial mass to decay (b) The average time taken for one-half of the original number of nuclei to decay (c) The time taken for one-half of the original number of nuclei to decay (d) The average time taken for one-half of the original number of nuclei to undergo one decay reaction.
  2. The activity of a radioactive sample is A. The rate of decay of the sample at this time is (a) A, (b) -A, (c) A ln2, (d) A/ln2
  3. The decay constant is equal to the probability that a nucleus will undergo radioactive decay. True or false?
  4. The decay constant is inversely proportional to the probability that a nucleus will undergo radioactive decay per unit time. True or false?
  5. During an experiment with a new alpha particle emitting sample in the laboratory the reading on a Geiger counter is 2.6 after 0.3 h. The reading is next taken 0.2 h after the first measurement and its value is 1.8. Find the time interval when the reading is 0.8.