(ii) Beryllium-9 has an atomic number of 4 and a mass number of 9. A nucleus of this isotope can be described using this symbol.

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5 Questions Q1. Beryllium-9 is a stable isotope of beryllium. (a) (i) State the meaning of the term stable. (ii) Beryllium-9 has an atomic number of 4 and a mass number of 9. A nucleus of this isotope can be described using this symbol. (1) Complete the sentence by putting a cross ( ) in the box next to your answer. The number of neutrons in this nucleus is (1) A 4 B 5 C 9 D 13 (iii) Which one of these symbols describes the nucleus of a different isotope of beryllium? Put a cross ( ) in the box next to your answer. (1) (b) A beryllium-9 nucleus absorbs a neutron.

6 After a short time the new nucleus splits into two neutrons and two alpha particles. (i) Complete the flow chart for this reaction. (ii) Compare this nuclear reaction with the fission of a uranium nucleus. (iii) A fission reaction can be the start of a chain reaction. Describe what needs to happen next to produce a chain reaction. (3) (Total for Question = 10 marks)

7 Q2. * Describe how the nuclear fission of uranium-235 is used to produce electricity in a nuclear power station. (6) Q3. Alpha, beta and gamma are types of ionising radiation. (a) State twoways in which gamma radiation is different from alpha radiation.

8 (b) (i) Complete the sentence by putting a cross ( ) in the box next to your answer. A beta particle is emitted by (1) A an alpha particle B a fusion particle C a gamma ray D an unstable nucleus (ii) Complete the sentence by putting a cross ( ) in the box next to your answer. A beta particle has an identical charge to (1) A an alpha particle B an electron C a neutron D a nucleus (c) Explain how an atom becomes ionised by radiation.

9 *(d) The removable lens of this old camera has four pieces of glass in it. One of the pieces of glass is radioactive. Its surface is covered with a thin layer of magnesium fluoride. Radioactive isotopes in the glass emit alpha, beta and gamma radiation in all directions. A scientist removes the lens from the camera. She measures the radiation coming from the back, front and side of the lens. The amount of radiation is different in each direction. No alpha radiation is detected. The readings are shown on the diagram. Explain why the readings in the three directions are different. (6)

10 (Total for Question is 12 marks) Q4. (a) Two isotopes of uranium are U-235 and U-238. Here are the symbols of the nuclei of these isotopes.

11 (i) Complete the sentence by putting a cross ( ) in the box next to your answer. The U-235 isotope has (1) A the same number of neutrons as U-238 B the same number of protons as U-238 C more neutrons than U-238 D more protons than U-238 (ii) U-235 is radioactive. When it decays, it releases an alpha particle. Describe an alpha particle. (b) U-235 can also be made to undergo fission. Describe what happens during nuclear fission. (4)

12 (c) Fission is used in nuclear reactors. Graphite is used as a moderator in nuclear reactors. Explain why a moderator is needed in a nuclear reactor. (Total for Question is 9 marks) Q5. Nuclear reactions (a) Complete the sentence by putting a cross ( ) in the box next to your answer. Two types of nuclear reaction are nuclear fission and nuclear fusion. Nuclear fission and nuclear fusion reactions both (1) A combine hydrogen nuclei B combine uranium nuclei C release neutrons D release energy (b) In 1989, two scientists called Pons and Fleischmann claimed to have produced cold fusion. Their claim has never been validated by the scientific community. Explain the phrase validated by the scientific community.

13 (c) Nuclear fusion is the main energy source for stars. Describe what happens in nuclear fusion. (3) *(d) Describe how the nuclear fission of uranium-235 is used to produce electricity in a nuclear power station. (6)

14 Q6. Alpha, beta and gamma are types of ionising radiation. * The removable lens of this old camera has four pieces of glass in it. One of the pieces of glass is radioactive. Its surface is covered with a thin layer of magnesium fluoride. Radioactive isotopes in the glass emit alpha, beta and gamma radiation in all directions. A scientist removes the lens from the camera. She measures the radiation coming from the back, front and side of the lens. The amount of radiation is different in each direction. No alpha radiation is detected. The readings are shown on the diagram.

15 Explain why the readings in the three directions are different. (6)

16 Mark Scheme Q1. Answer Acceptable answers Mark (a)(i) does not emit (ionising) radiation / no (radioactive) decay it is not radioactive (1) (a)(ii) B5 (a)(iii) (1) (1) A (b)(i) helium beryllium (1) (1) helium (b)(ii) a comparison which describes any three of the following: daughter daughter in right hand boxes (3) similarities: differences: produce (more) neutrons (1) produce 'daughter' (nuclei) (1) release energy (1) split a (bigger) nucleus (1) (triggered by) a neutron coming in (1) nucleus becomes unstable (before splitting) (1) uranium daughters are different from each other/ different elements / smaller nuclei for daughters do not accept split an atom neutron is absorbed

17 beryllium daughters are the same (1) uranium daughters are heavier than beryllium daughters (1) (b)(iii) a description including: neutron(s) (from first fission) (1) (go on to) cause another fission (1) collide with another nucleus /atom Q2. Question Indicative Content Number QWC * A description including some of the following stages Mark (6) Fission absorption of slow moving / thermal neutron by U-235 to produce daughter nuclei, two or more neutrons and two or more neutrons and Controlled chain reaction use of moderators to produce thermal neutrons use of control rods to capture neutrons idea of keeping number of further fissions to just over one per fission reaction Energy transfer

18 (kinetic) energy (of fission products) is converted to thermal energy use of coolant to transfer the thermal energy (from the reactor vessel to a heat exchanger) to produce steam use of steam to drive a turbine use of turbine to {drive a generator / produce electricity} Level 0 No rewardable content a limited description e.g. heat from the reactor makes steam for the turbine the answer communicates ideas using simple language and uses limited scientific terminology spelling, punctuation and grammar are used with limited accuracy some description including some points from all three stages or most points from any two stages the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately spelling, punctuation and grammar are used with some accuracy a a detailed description including most points from all three stages: fission, controlled chain reaction and energy transfer the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, punctuation and grammar are used with few errors Q3.

19 (a)(i) Answer Acceptable answers Mark Any twoof: Reverse arguments Gamma is a wave (1) Alpha is a helium nucleus (1) Alpha is charged (1) Alpha has a mass (1) Gamma penetrates further/ highly (1) Gamma weakly ionising (1) Gamma travels faster (1) em radiation Gamma has no charge Gamma has no mass examples of penetrating power alpha highly ionising ignore vague comments eg stronger Ignore uses and dangers (b)(i) D (1) (b)(ii) B (1) (c) An explanation linking: electron(s) (1) is/are lost/gained (1) do not allow positive electron knocked off / removed/ released Indicative Content M QWC *(d) An explanation including some of the following points: Radiation from the front of the lens ( Alpha particles absorbed by glass Beta particles do not penetrate glass Gamma rays pass through glass Background radiation varies There is a large difference in size between front and b Radiation detected is gamma rays only Radiation from side of the lens Alpha particles cannot penetrate aluminium Beta particles are absorbed by aluminium Gamma rays pass through aluminium There is a small/no difference in size between front an Perhaps a few gamma rays absorbed by aluminium Background radiation varies Likely to contain gamma rays only May be different from front count due to random natu emissions There is a large difference in size between front and b Difference between front and back counts due to beta Radiation from the back of the lens Alpha particles absorbed by coating and/or glass Beta particles are emitted the from rear surface Gamma rays emitted from radioactive glass Background radiation varies Radiation is both beta particles and gamma rays Level 0 No rewardable content a limited explanation mentioning two unrelated points, but without linking them properly, e.g. beta particles are stopped by thick

20 aluminium, there is most radiation behind the lens the answer communicates ideas using simple language and uses limited scientific terminology spelling, punctuation and grammar are used with limited accuracy a simple explanation mentioning some points with an appropriate linkage to oneof the readings e.g. no beta particles escape forwards because the glass absorbs them OR only gamma rays escape to the side because the aluminium stops alpha and beta particles the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately spelling, punctuation and grammar are used with some accuracy a detailed explanation mentioning some of the points with appropriate linkage to a comparison of at least twoof the readings e.g. no beta particles escape forwards because the glass absorbs them, but beta particles can escape backwards so that count is higher OR only gamma rays can get through the glass and the thick aluminium, so the front and side counts are about the same the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, punctuation and grammar are used with few errors Total for question = 12 marks Q4. Answer Acceptable answers Mark (a)(i) B (1) (a) (ii) (equivalent to a) helium nucleus Two protons and two neutrons for 2 marks helium/mass of 4 for 1 mark charge of +2 for 1 mark (b) correct statement of any property for 1 mark A description to include any four of the following neutron is captured by a U-235 nucleus nucleus (is) unstable nucleus splits into 2 daughter nuclei (of similar size) (2 or more) neutrons are released energy is released (c) An explanation linking collides with /absorbed by (U-235) nucleus metastable named isotopes (4)

21 moderator slows down (absorbs energy from) neutrons more likely to be captured /cause fission (if it collides withreverse argument a U-235 nuclei) Q5. Question Answer Acceptable answers Mark Number (a) D (1) Question Number (b) Answer Acceptable answers Mark An explanation linking the following points idea that the procedure has been checked to confirm consistent results (1) (by) other reputable {scientists /organisations / peers} (1) Question Number (c) Answer Acceptable answers Mark A description including three of the following points (3) {hydrogen / small} nuclei (1) join or fuse (1) to form {helium / larger} nuclei (1) energy is released (1) Question Number Indicative Content Mark

22 QWC *(d) A description including some of the following stages (6) Fission absorption of slow moving / thermal neutron by U-235 to produce daughter nuclei, two or more neutrons and two or more neutrons and Controlled chain reaction use of moderators to produce thermal neutrons use of control rods to capture neutrons idea of keeping number of further fissions to just over one per fission reaction Energy transfer (kinetic) energy (of fission products) is converted to thermal energy use of coolant to transfer the thermal energy (from the reactor vessel to a heat exchanger) to produce steam use of steam to drive a turbine use of turbine to {drive a generator / produce electricity} Level 0 No rewardable content

23 1 1-2 a limited description e.g. heat from the reactor makes steam for the turbine the answer communicates ideas using simple language and uses limited scientific terminology spelling, punctuation and grammar are used with limited accuracy some description including some points from all three stages or most points from any two stages the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately spelling, punctuation and grammar are used with some accuracy a a detailed description including most points from all three stages: fission, controlled chain reaction and energy transfer the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, punctuation and grammar are used with few errors Q6. Indicative Content M An explanation including some of the following points: Radiation from the front of the lens ( Alpha particles absorbed by glass Beta particles do not penetrate glass Gamma rays pass through glass Background radiation varies There is a large difference in size between front and b Radiation detected is gamma rays only Radiation from side of the lens Alpha particles cannot penetrate aluminium Beta particles are absorbed by aluminium Gamma rays pass through aluminium There is a small/no difference in size between front an Perhaps a few gamma rays absorbed by aluminium Background radiation varies

24 Powered by TCPDF ( Likely to contain gamma rays only May be different from front count due to random natu emissions There is a large difference in size between front and b Difference between front and back counts due to beta Radiation from the back of the lens Alpha particles absorbed by coating and/or glass Beta particles are emitted the from rear surface Gamma rays emitted from radioactive glass Background radiation varies Radiation is both beta particles and gamma rays Level 0 No rewardable content a limited explanation mentioning two unrelated points, but without linking them properly, e.g. beta particles are stopped by thick aluminium, there is most radiation behind the lens the answer communicates ideas using simple language and uses limited scientific terminology spelling, punctuation and grammar are used with limited accuracy a simple explanation mentioning some points with an appropriate linkage to oneof the readings e.g. no beta particles escape forwards because the glass absorbs them OR only gamma rays escape to the side because the aluminium stops alpha and beta particles the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately spelling, punctuation and grammar are used with some accuracy a detailed explanation mentioning some of the points with appropriate linkage to a comparison of at least twoof the readings e.g. no beta particles escape forwards because the glass absorbs them, but beta particles can escape backwards so that count is higher OR only gamma rays can get through the glass and the thick aluminium, so the front and side counts are about the same the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, punctuation and grammar are used with few errors