A star has a power output of 8.9326 W. Determine by how much its mass changes per year. A lithium-7 nucleus contains 3 protons and 4 neutrons. Nuclear physicists in an isolated nation use a non-standard definition of the kilogramme. They have the following data: Mass of Lithium-7 = 1.51459E-26 kg Mass of neutron = 2.1774E-27 kg Mass of proton = 2.1744E-27 kg Determine their value for the mass defect of Lithium-7.A radioactive isotope has a decay constant of 8.04E-03 is. Calculate the time taken for three quarters of a sample of the isotope to decay. A sample of radioactive material contains 7.0E+10 unstable nuclei with a decay constant of 1.65E-06 /5. (a) Calculate how many nuclei remain after 1.2E+06 5. select units v (b) Determine the activity of the sample after 1.2E+06 s. Give your answer as a positive value. select units v