Edexcel GCSE Combined Science: Physics: Particle Model and Radioactivity
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.
Alpha, beta and gamma radiation are the three main types of nuclear radiation emitted by unstable nuclei. They differ in their nature, their ionising power and how far they penetrate materials.
Compare the three types of nuclear radiation — alpha, beta and gamma — in terms of what each one is, their penetrating power, and their ionising power. (6 marks)
In a core practical, a student measured the density of a small regular metal block. They found its mass using a balance and its volume by measuring its sides. The measurements were:
| Quantity | Measurement |
|---|---|
| Mass of block | 216 g |
| Volume of block | 80 cm³ |
(a) Calculate the density of the metal. Use the equation ρ=Vm. Show your working and give the unit. (3 marks)
(b) The student is told that the density of pure aluminium is about 2.7 g/cm³. State whether the block could be made of pure aluminium, and justify your answer using your result. (1 mark)
A radioactive isotope has a half-life of 6 hours. A sealed sample initially contains nuclei that give a measured activity of 800 Bq. The activity is measured every 6 hours, as shown below.
| Time / hours | Activity / Bq |
|---|---|
| 0 | 800 |
| 6 | 400 |
| 12 | 200 |
| 18 | ? |
(a) Define what is meant by the half-life of a radioactive isotope. (1 mark)
(b) Using the pattern in the table, calculate the activity that would be measured at 18 hours. Show your working. (2 marks)
When a solid is heated, it can melt to become a liquid. During melting, energy is supplied continuously but the temperature stays constant until all the solid has melted.
(a) Explain, in terms of the particle model, why the temperature stays constant while a solid is melting, even though energy is still being supplied. (2 marks)
(b) State the name given to a change of state in terms of internal energy — explain whether the internal energy of the substance increases, decreases or stays the same during melting. (1 mark)
When dealing with radioactive sources it is important to understand the difference between irradiation and contamination.
Explain the difference between irradiation and contamination by a radioactive source. (2 marks)
Atoms of the same element can exist as different isotopes.
State what is meant by isotopes of an element. (1 mark)