6 exam-style questions with full mark schemes and model answers. Write your own answer and the AI examiner marks it against the mark scheme.
Learn this properly: The Atom and the Nuclear ModelA hospital physicist has three sealed radioactive sources on the bench. One is an alpha (α) emitter, one a beta (β) emitter and one a gamma (γ) emitter.
Compare the three types of nuclear radiation. In your answer you should describe what each type is (its nature), and compare their penetrating power and their ionising power, referring to the materials that stop each one. (6 marks)
A freshly prepared radioactive source has an activity of 800 Bq. A student measures its activity over the next day (correcting for background radiation) and finds that it has fallen to 50 Bq.
(a) Show that the activity has fallen through four half-lives, and hence determine the number of half-lives that have passed. (2 marks)
(b) The total time for the fall from 800 Bq to 50 Bq was 24 hours. Calculate the half-life of the source. Show your working and give the unit. (2 marks)
A radium nucleus decays by emitting an alpha particle and becoming a radon (Rn) nucleus. The decay is shown by the incomplete nuclear equation below:
88226Ra→ ZARn+ 24He
(a) Determine the values of the mass number A and the atomic number Z of the radon nucleus. Show how you use conservation of mass number and atomic number. (2 marks)
(b) State what an alpha particle is made of. (1 mark)
Carbon-14 is a radioactive isotope of carbon. A carbon-14 nucleus decays by beta (β) decay to become a nitrogen (N) nucleus.
(a) Complete the nuclear equation for this decay by giving the mass number and atomic number of the nitrogen nucleus and of the beta particle:
614C→ ??N+ ??e (2 marks)
(b) Explain what is meant by saying that carbon-14 and carbon-12 are isotopes of each other. (1 mark)
In a nuclear power station, energy is released from uranium fuel by the process of nuclear fission. In the core of the Sun, energy is released by nuclear fusion.
Compare nuclear fission with nuclear fusion, giving one clear difference between the two processes in terms of the nuclei involved. (2 marks)
The nuclear model of the atom describes a tiny central nucleus surrounded by electrons.
State the names of the two types of particle found in the nucleus of an atom. (1 mark)