Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Radioactivity
46 practice questions
Topics covered
Practice questions
21–23 of 23 · Normal
Question 21
6 marks · Normal
Answer and see the solution →A radioactive source emits both alpha and gamma radiation. The source is tested in a lab using a Geiger-Muller (GM) tube, as shown below.
(a)[2 marks]Describe how the GM tube is used to detect ionising radiation. Name one other way, apart from a GM tube, that ionising radiation can be detected.
(b)[2 marks]A student places a thin sheet of paper between the source and the GM tube, and records the count rate. She then places a thick lead block instead and records the count rate again. Explain what you would expect to happen to the count rate in both cases, and what this shows about the properties of alpha and gamma radiation.
(c)[2 marks]Alpha particles are helium nuclei. State the number of protons and neutrons in an alpha particle. How does the emission of an alpha particle affect the atomic number and mass number of a nucleus?
Question 22
5 marks · Normal
Answer and see the solution →A radioactive isotope of nitrogen, , decays by beta minus emission. A scientist is studying nuclear stability and writes an equation for this decay.
(a)[2 marks]Write the balanced nuclear equation for the beta minus decay of .
(b)[2 marks]State, with reasons, how the numbers of protons and neutrons change in the nucleus as a result of this decay.
(c)[1 mark]Explain why some isotopes with the same number of protons as are stable, while others are unstable.
Question 23
5 marks · Normal
Answer and see the solution →A student investigates the decay of a radioactive isotope by measuring its activity (in Bq). The data below shows the measured activity at 10-minute intervals, after correcting for background radiation.
Radioactive decay data Time (min) Activity (Bq) 0 480 10 240 20 120 30 60 (a)[1 mark]Describe what is meant by the half-life of a radioactive isotope.
(b)[2 marks]Use the table to determine the half-life of this isotope. Show your working.
(c)[2 marks]Explain why the measured activity falls as time passes.