1. 1
   A solar physicist gives a public talk explaining that the Sun is a medium-sized star, made up mostly of hydrogen and helium, which radiates energy across a wide range of the electromagnetic spectrum.

   (a)

   A solar physicist explains that the Sun is classified as a medium-sized star, made up mostly of two chemical elements. Which two elements make up most of the Sun's composition?

   [1 mark]

   • AHydrogen and helium
   • BOxygen and nitrogen
   • CCarbon and iron
   • DSilicon and oxygen

   (b)

   The physicist explains that the Sun radiates most of its energy across three particular regions of the electromagnetic spectrum. Which three regions are these?

   [1 mark]

   • AMicrowaves, visible light, and gamma rays
   • BRadio waves, microwaves, and infrared
   • CX-rays, gamma rays, and radio waves
   • DInfrared, visible light, and ultraviolet

   (c)

   State the name of the nuclear process that powers the Sun, and state which two elements are involved as the reactant and product of this process.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An energy researcher explains to a group of engineers that scientists around the world are trying to develop a power station based on the same nuclear process that powers the Sun, in order to generate electricity on Earth without producing carbon dioxide.

   (a)

   An energy researcher explains that scientists are trying to develop a power station based on the same nuclear process that powers the Sun, in order to generate electricity on Earth. What is this process called?

   [1 mark]

   • AChemical combustion
   • BNuclear fission
   • CNuclear fusion
   • DRadioactive decay

   (b)

   The researcher explains that achieving this process on Earth requires extremely high temperatures and pressures. Why is this the case?

   [1 mark]

   • ATo cool the hydrogen fuel down to absolute zero
   • BTo force positively charged nuclei close enough together to overcome their electrostatic repulsion
   • CTo increase the electrical resistance of the fuel
   • DTo convert the hydrogen fuel into a solid

   (c)

   Explain why current research into using nuclear fusion to generate electrical power on Earth is described as ongoing, rather than already being an established method of generating electricity like existing nuclear fission power stations.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A school astronomy club is comparing the Sun with other stars of very different sizes, as part of a project on the composition and life cycle of stars.

   (a)

   Explain what is meant by describing the Sun as a 'medium-sized' star, and describe the composition of the Sun in terms of the elements it contains.

   [3 marks]

   (b)

   The club learns that the Sun's stability depends on a balance between two opposing effects acting on it. Explain what these two effects are, and explain what would happen to the Sun if the balance between them were disrupted, for example if the rate of nuclear fusion at its centre were to suddenly decrease.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A science museum is designing an exhibit describing the Sun's composition, its nuclear power source, and its role as the primary source of energy driving almost all of Earth's energy resources.

   (a)

   Describe the composition of the Sun, the nuclear process by which it generates its energy, and the regions of the electromagnetic spectrum in which it radiates most of its energy, and explain why the Sun is described as the main source of energy for almost all of Earth's energy resources, giving examples of exceptions to this.

   [6 marks]

   (b)

   The exhibit also includes a section describing ongoing research into using nuclear fusion, the same process that powers the Sun, to generate electricity on Earth in the future. Explain the key differences between the conditions under which fusion occurs naturally inside the Sun and the conditions engineers must try to create and sustain in an experimental fusion reactor on Earth, and explain why, despite decades of research, a commercially viable fusion power station has not yet been built.

   [6 marks]

   Total for question 4: 12 marks

End of questions