1. Half Life After one half life half of a sample is left. After 4 half-lives ___ is left. A.1/2 B.1/4 C.1/8 D.1/16

2. decay constant The half-life of nucleus A is twice as long as the half-life of nucleus B. The decay constant of nucleus A is ___ the decay constant of nucleus B. A.1/2 B.1/4 C.twice D.4 times

3. Half Life After 2 half-lives the activity of a sample is ___ its initial value. A.1/2 B.1/4 C.twice D. 4 times

4. PAL 15 O decays via beta-plus decay. a) Find the daughter isotope in the decay. b) If 10% of a sample of 15 O is left after 6.77 min, find the decay constant. 0.340 min -1. c) Use the decay constant to calculate the half-life. 2.04 min d) What percent is left after 1 hr? 1.37e-7%