7:38 PM Mon Dec 11 Name: 1 of 1 Date: Unit III: Nuclear Half-Life Assignment N = No No 1/ Period: /20 1. How long will it take for 30 g of 90Sr to decay to 7.5 g? The half-life of this isotope is 28.1 years. 2. What mass of 16N will be left from a 64 g sample after 21.6 sec? The half-life of this isotope is 7.2 sec. 3. How many half-lives will it take for a radioisotope to decay from 100 g to 6.25 g? 4. The half-life of 222 Rn is 3.82 days. What fraction of a sample would remain after 11.46 days? 5. How long will it take for 28 g of 239Pu to decay to 3.5 g? The half-life of this isotope is 24,400 years. 6. What fraction of a sample of H will be left after 36.9 years? The half-life of this isotope is 12.3 years. 7. The half-life of 53 Fe is 8.5 min. If 42.5 mins pass and 12 g remains, what mass did the sample start as? VPN 80%