1. The age of the Earth is about 4.543 x 109 years. When the Earth formed, a certain radioisotope with a half-life of 1.05 x 10" years was created.If the radioisotope stated as 250 mg, how much would remain since the Earth's formation? [3 marks] 2. Tritium, a by-product of the CANDU nuclear power reactor, has a half life of 12.3 years. How much time is required for its radioactivity to reach one-quarter of its original level? [3 marks] 3. Use a periodic table to complete each of the following nuclear equations: [2 marks] 230 226 88 Ka + a. 214 Pb 82 b.4. Determine the mass defect and energy produced for the following reaction [6 marks] 235 140 92 Utin - 55 CS + 37 Rb + 3(on) + energy . mass of U = 235.044 u . mass of Cs = 139.909 u mass of Rb = 92.922 u . mass of neutron = 1.009 u