A bromine-82 nucleus decays in two stages. Radiation R is emitted in the first stage and gamma radiation is emitted in the second stage. After both stages, the nucleus is krypton-82.
| Point in sequence | Number of protons | Number of neutrons |
|---|---|---|
| before stage 1 | 35 | 47 |
| after stage 1 | 36 | 46 |
| after stage 2 | 36 | 46 |
Determine what radiation R is. Use conservation of mass number and charge to support your answer.
A bromine-84 nucleus decays by the same two stages.
Calculate the number of neutrons in the nucleus formed after both stages.
Two students explain the changes.
Leah says, 'In stage 1, a neutron is emitted from the nucleus. In stage 2, the nucleus loses energy as gamma radiation, and the numbers of protons and neutrons do not change.'
Ravi says, 'In stage 1, a neutron changes into a proton. In stage 2, a proton changes into a neutron and energy is given out as gamma radiation.'
Explain which parts of each student's explanation are correct. Use the data in the table to support your answer.
120 exam-style questions on Edexcel GCSE Physics 6.3 Nuclear equations and decay, covering 6.3.1 Beta-minus and beta-plus decay, 6.3.2 Effects of decay on the nucleus, and 6.3.3 Balancing nuclear equations. Each one has a worked solution and a mark scheme showing where the marks go.