Two samples initially contain the same number of undecayed nuclei. They emit the same type and energy of radiation and are compared at the same distance with identical shielding. P has a much shorter half-life than Q. Which statement correctly compares the initial exposure rates and the time for activity to halve?
P gives a lower initial exposure rate and its activity halves sooner.
P gives a higher initial exposure rate and its activity halves sooner.
P gives a lower initial exposure rate and its activity halves later.
P gives a higher initial exposure rate and its activity halves later.
97 exam-style questions on Edexcel GCSE Physics 6.5 Uses and dangers of radioactivity, covering 6.5.1 Uses of radioactivity, 6.5.2 Dangers of ionising radiation and precautions, 6.5.3 Half-life and radiation dangers, 6.5.4 Safety precautions for radiation exposure, and 6.5.5 Contamination and irradiation. Each one has a worked solution and a mark scheme showing where the marks go.