1. 1
   A hospital radiographer explains to a patient that an isotope of iodine, iodine-131, with a nucleon number of 131 and a proton number of 53, is used in some medical scans of the thyroid gland.

   (a)

   A hospital radiographer explains that an isotope of iodine, iodine-131, is used in some medical scans. Iodine-131 has a proton number of 53. What does the proton number tell you about the nucleus?

   [1 mark]

   • AThe number of protons in the nucleus
   • BThe total number of protons and neutrons in the nucleus
   • CThe number of electrons orbiting the nucleus only
   • DThe number of neutrons in the nucleus

   (b)

   Iodine-131 has a nucleon number of 131. How many neutrons are there in a nucleus of iodine-131?

   [1 mark]

   • A53
   • B78
   • C131
   • D184

   (c)

   Iodine-123 is a different isotope of iodine, also used in medical scans. State what is meant by the term isotope, and state one way in which the nucleus of iodine-123 differs from the nucleus of iodine-131.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A nuclear power station generates electricity using a reactor in which uranium-235 nuclei are struck by neutrons, causing them to split apart and release energy, which is used to heat water and drive turbines.

   (a)

   What is the name of this nuclear process?

   [1 mark]

   • AIonisation
   • BNuclear fusion
   • CRadioactive decay
   • DNuclear fission

   (b)

   In the Sun, hydrogen nuclei join together to form helium nuclei, releasing energy in the process. What is the name of this nuclear process?

   [1 mark]

   • ABeta decay
   • BNuclear fission
   • CNuclear fusion
   • DElectrostatic induction

   (c)

   State one similarity and one difference between nuclear fission, as used in the power station reactor, and nuclear fusion, as it occurs in the Sun.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A geology student studies a sample of rock containing the radioactive isotope potassium-40, which is known to decay by beta emission into calcium-40, and uses this decay to help estimate the age of the rock.

   (a)

   Write a nuclide equation for this beta decay, and explain, in terms of proton number and nucleon number, why the daughter nucleus is a different element from the parent nucleus.

   [3 marks]

   (b)

   Some other rock samples contain the isotope uranium-238, which decays by alpha emission into thorium-234. Write a nuclide equation for this alpha decay, and explain, in terms of the numbers of protons and neutrons, why alpha decay tends to increase the stability of a very heavy, neutron-rich nucleus like uranium-238.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   An energy company is comparing existing nuclear fission power stations with proposed future nuclear fusion power stations, as part of a long-term plan to reduce carbon emissions from electricity generation.

   (a)

   An energy company is comparing nuclear fission power stations with proposed future nuclear fusion power stations. Explain, in terms of the structure of the nucleus, what happens during nuclear fission and what happens during nuclear fusion, describing the changes in mass and the release of energy in each process (without using specific numerical values), and explain why current nuclear power stations use fission rather than fusion.

   [6 marks]

   (b)

   The energy company also needs to explain to investors how nuclide notation and the concept of proton number and nucleon number are used to track the changes that occur during a fission chain reaction, in which uranium-235 absorbs a neutron, splits into barium-141 and krypton-92, and releases further neutrons. Explain how the total nucleon number and total proton number are conserved during this fission reaction, and describe why the released neutrons are important for sustaining a chain reaction.

   [6 marks]

   Total for question 4: 12 marks

End of questions