Question 13 Nuclear fusion is a process which releases large amounts of energy and takes place in the core of stars like our Sun. a) Describe what is meant by nuclear fusion and the conditions necessary for it to take place. [Suggested word count 100] b) It is believed that the first elements to exist in the early Universe were hydrogen and helium. What role has nuclear fusion taken in the creation of the world around us? [Suggested word count 200] [4.3] Question 14 The following table shows the percentage of the intensity of radiation that passes through sheets of paper, aluminium and lead from three radioactive sources, each emitting only one kind of radiation. 1 sheet 80 gsm 3mm thick 5 mm thick lead paper aluminium plate plate source A 99.9% 90% 50% source B 50% 0.1% source C 95% 1% a) Identify the type of radiation being emitted from each source. Completed forms to be made available for external moderation. b) The penetrating power of nuclear radiation is closely linked to its ability to ionize the material it is passing through. Explain why some types of radiation may be more strongly ionising than others. [Suggested word count 150] [5.1]