1. The half-life of cesium-137 is 3.2 years. If the initial mass of a sample of cesium-137 is 1.0kg, how much will remain after 151 years? 2. Given that the half-life of carbon-14 is 5730 years, consider a sample of fossilized wood that, when alive, would have contained 24g of carbon-14. It now contains 1.5g of carbon-14. How old is the sample? 3. A 64-g sample of germanium-66 is left undisturbed for 1.5 hours. At the end of that period, only 2.0g remain. What is the half-life of this material? 4. With a half-life of 28.2 years, how long will it take for 1g of strontium-90 to decay to 125mg ? 5. A sample of air from a basement is collected to test for the presence of radon-222, which has a half-life of 3.8 days. However, delays prevent the sample from being tested until 7.6 days have passed. Measurements indicate the presence of 6.5g of radon-222. How much radon-222 was present in the sample when it was initially collected? 6. A 0.500M solution of iodine-131, which has a half-life of 8.0 days, is prepared. After 40.0 days, how much iodine will remain in 1.0L of solution? Express the results in moles