1. The problem statement, all variables and given/known data The nuclear processes obey certain rules. I.e. Conservation of energy and mass Conservation of charge Conservation of spin Conservation of momentum Conservation of lepton and baryon numbers Use the following examples to discuss these various rules in the following situations: 1. The positron (beta plus) decay of oxygen -16 to nitrogen -16 2. Thermal neutron fission of uranium -235 3. The interaction of a gamma ray photon with a nucleus in a bubble chamber liquid to produce an electron positron pair 4. It is suggested that a proton can react with a pi particle to form a kaon. The quark compositions of these mesons are K0 down plus anti strange and pi down and anti up. Deduce whether the reaction is possible. 2. Relevant equations Question 4. p+ + π - --> K0 + n0 3. The attempt at a solution I understand each of the laws briefly. Im unsure how to explain the answers. Heres my answer for Q1: In β+ decay, or "positron emission", the weak interaction converts a nucleus into its next-lower neighbour on the periodic table while emitting an positron (e+) and an electron neutrino (νe). If oxygen-16 was to undergo positron emission (beta plus decay), a proton in its nucleus would transform into a neutron (mediated by the weak force). The oxygen-16 would become nitrogen-16, and we'd see a positron and a neutrino appear. This obeys the law of conservation of energy as; Albert Einstein announced his discovery of the equation E = mc2 and the Law of Conservation of Mass-Energy: the total amount of mass and energy in the universe is constant. In this beta decay the mass remains constant.