Physics 3U
Nuclear Decay/Half-life questions
1. Uranium – 238 decays by alpha particle emission. What element (name
and mass number) is created?
2. Americium – 241 decays by alpha decay. What new element is created?
3. Carbon – 14 decays by beta decay. What new element is created?
4. Cesium – 137 decays by beta decay. What new element is created?
5. Postulate a decay that would turn another element into gold.
6. Carbon – 14 is used for radioactive dating. The half-life of carbon – 14 is
5730 years. If 3g of C-14 was in a sample 2000 years ago, how much C –
14 is in the sample now?
7. The half-life of sodium – 25 is 59.1 seconds. How long would it take for
16g of sodium – 25 to be reduced to 1g of sodium – 25?
8. Sodium – 25 decays by beta decay. What new element is created?
9. The half-life of uranium – 232 is 68.9 years. How much of a 1 kg sample
would be left after 100 years?
Answers: 1. thorium – 234
2. neptunium – 237
3. Nitrogen – 14
4. barium – 137
5. beta decay of platinum, alpha decay of thallium
6. 2.35g
7. 236 seconds
8. magnesium – 25
9. 365g