Plutonium-239 (²³⁹Pu) is an isotope that is used as the fuel in some nuclear reactors. [Figure 8.1]

1. (a)State the names of the types of particles found in a nucleus of plutonium-239, and state how many there are of each type.[2]
2. (b)(i)Fig. 8.1 shows the nuclear fission process that occurs within the fuel rods of the nuclear reactor. Explain how the fission process produces a chain reaction.[2]
3. (b)(ii)Explain how control rods are used to increase and decrease the rate of the chain reaction in a nuclear reactor.[2]
4. (c)Plutonium-239 decays by the emission of an alpha particle (α-particle). State two differences between an alpha particle and a beta particle (β-particle).[2]
5. (d)(i)Alpha particles from the radioactive source are detected in a cloud chamber or with a spark counter. Draw a labelled diagram of either a cloud chamber or a spark counter. Label the position of the radioactive source with an S.[2]
6. (d)(ii)State what causes the tracks in a cloud chamber or state what causes the sparks in a spark counter.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.