1. One of the nuclides in spent nuclear fuel is U-235, an alpha emitter with a half-life of 703 million years. How many years will it take for the amount of U-235 to reach 30.0% of its initial amount?

2. A radioactive sample contains 3.10 g of an isotope with a half-life of 4.66 days. What mass of the isotope remains after 7.99 days?

(Keep all numbers all the way through and only round at the very end!)