Exampro GCSE Physics. P2 Fission, Fusion and life cycle of a star self study questions - Higher tier. Name: Class: Author: Date: Time: PDF

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Exampro GCSE Physics P2 Fission, Fusion and life cycle of a star self study questions - Higher tier Name: Class: Author: Date: Time: 68 Marks: 68 Comments: Page of 26 Q. Describe briefly how stars such
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Exampro GCSE Physics P2 Fission, Fusion and life cycle of a star self study questions - Higher tier Name: Class: Author: Date: Time: 68 Marks: 68 Comments: Page of 26 Q. Describe briefly how stars such as the Sun are formed (Total 2 marks) Q2. (a) Nuclear power stations generate about 4% of the world s electricity. (i) Uranium-235 is used as a fuel in some nuclear reactors. Name one other substance used as a fuel in some nuclear reactors.... () (ii) Energy is released from nuclear fuels by the process of nuclear fission. This energy is used to generate electricity. Describe how this energy is used to generate electricity. Do not explain the nuclear fission process (3) Page 2 of 26 (b) The diagram shows the nuclear fission process for an atom of uranium-235. Complete the diagram to show how the fission process starts a chain reaction. Page 3 of 26 (c) The diagram shows the cross-section through a nuclear reactor. The control rods, made from boron, are used to control the chain reaction. Boron atoms absorb neutrons without undergoing nuclear fission. Why does lowering the control rods reduce the amount of energy released each second from the nuclear fuel? (Total 8 marks) Q3. (a) Nuclear power stations use the energy released by nuclear fission to generate electricity. (i) Explain what is meant by nuclear fission Page 4 of 26 (ii) How does nuclear fission lead to a chain reaction? You may give your answer as a labelled diagram () (b) Although nuclear fuels are relatively cheap the total cost of generating electricity using nuclear fuels is expensive. Why? () (c) The table compares the energy released from kg of coal and kg of uranium. Coal 29 MJ MJ = joules Uranium MJ State one benefit to the environment of using a concentrated fuel like uranium to generate electricity rather than using the energy from coal () (Total 5 marks) Q4. The energy radiated by a main sequence star like the Sun is released by a nuclear fusion reaction in its core. Read the following information about this reaction then use it to answer the questions below. The net result of the nuclear fusion reaction is that four hydrogen nuclei produce one helium nucleus. There is a loss of mass of 0.7%. For nuclear fusion to occur nuclei must collide at very high speeds. The energy released during the reaction can be calculated as shown: energy released [J] = loss of mass [kg] (speed of light [m/s²]) (The speed of light is m/s) Page 5 of 26 (a) Calculate the energy released when g of hydrogen fuses to form helium. (Show your working.) (4) (b) The table shows the lifetimes and surface temperatures of main sequence stars with different masses. MASS OF STAR [SUN = ] LIFETIME ON MAIN SEQUENCE [MILLION OF YEARS] SURFACE TEMPERATURE * [KELVIN] [* The higher the surface temperature of a star, the higher the temperature and pressure in its core.] (i) Describe the relationship between the lifetime of a main sequence star and its mass Page 6 of 26 (ii) Suggest an explanation for this relationship (3) (Total 9 marks) Q5. (a) Explain how stars produce energy (b) What evidence is there to suggest that the Sun was formed from the material produced when an earlier star exploded? () (c) It is thought that gases from the massive star Cygnus X- are spiralling into a black hole. (i) Explain what is meant by the term black hole Page 7 of 26 (ii) What is produced as the gases from a star spiral into a black hole?... () (Total 6 marks) Q6. The diagram, drawn below, places stars in one of four groups. Where a star is placed on the diagram is determined by the surface temperature and relative luminosity of the star. A star with a relative luminosity of, emits the same amount of energy every second as the Sun. (a) The Sun will spend most of its life cycle as a main sequence star. This is the stable period of the Sun s life cycle. What happens to cause the stable period in the life cycle of a star to end? () Page 8 of 26 (b) Use the information in the diagram to describe what will happen to the Sun after the stable period ends. (3) (Total 4 marks) Q7. (a) The diagram shows what can happen when the nucleus of a uranium atom absorbs a neutron. (i) What name is given to the process shown in the diagram?... () Page 9 of 26 (ii) Explain how this process could lead to a chain reaction. You may wish to add further detail to the diagram to help your answer (iii) How does the mass number of an atom change when its nucleus absorbs a neutron?... () Page 0 of 26 (b) Uranium-235 is used as a fuel in some nuclear reactors. Source: adapted from Physics Matters, by Nick England. Published by Hodder and Stoughton, 989. Reproduced by permission of Hodder and Stoughton Ltd. The reactor contains control rods used to absorb neutrons. Suggest what happens when the control rods are lowered into the reactor (Total 6 marks) Page of 26 Q8. The diagram shows part of the life cycle of a star which is much bigger than the Sun. (a) (i) What is the relationship between the masses of the dust and gas in the cloud in Stage 2 and the force of gravity between them? () (ii) What is the relationship between the distance apart of the dust and gas in the cloud in Stage 2 and the force of gravity between them? () Page 2 of 26 (b) In Stage 3 the star remains stable for millions of years. Explain why (c) What happens in Stage 4? (Total 6 marks) Q9. The flowchart shows a simple version of the life cycle of a star that is much more massive than the Sun. (a) What causes the change from Stage X to Stage Y? () Page 3 of 26 (b) For most of its time in Stage Y, the star is stable. Explain why the star remains stable. (c) (i) Explain how a star is able to produce energy in Stage Y (ii) Why is a star in Stage Y able to give out energy for millions of years? () (d) What happens to the elements produced in a supernova? () (Total 7 marks) Page 4 of 26 Q0. This passage is from a web page. Our nearest star, the Sun The pie chart shows the proportions of chemical elements in the Sun. Most of the Sun s helium has been produced from the Sun s hydrogen by the process of nuclear fusion. This process also produces vast quantities of energy. The process takes place in the core of the Sun at a temperature of about 5 million C and has been going on for about 4.5 billion years. During this period of time, the Sun has remained stable and scientists think that it will remain stable for several billion years into the future. (a) Explain why the Sun remains stable. (3) (b) A scientific opinion is expressed on this web page. Identify this opinion and suggest how scientists could justify it. (Total 5 marks) Page 5 of 26 Q. Read this statement from a website. Immediately after the big bang, at the start of the Universe, there were only atoms of the element hydrogen (H). Now there are over one hundred elements. Scientists think that all the elements on Earth are also present throughout the Universe. (a) Explain how atoms of the element (He) are formed in a star. (b) Explain how atoms of very heavy elements, such as gold (Au), were formed. (c) Scientists have only examined a tiny fraction of the Universe. What is the basis for scientists thinking that the elements found on Earth are present throughout the Universe? () (Total 5 marks) Q2. (a) As part of its life cycle, a star changes from being a protostar to a main sequence star. Explain the difference between a protostar and a main sequence star. Page 6 of 26 (b) The early Universe contained only atoms of hydrogen. The Universe now contains atoms of over one hundred different elements. Explain how the different elements now contained in the Universe were formed. (3) (Total 5 marks) Page 7 of 26 M. formed from dust or gas (unless in atmosphere) which is pulled together by gravitational forces high temperature inside [2] M2. (a) (i) plutonium (239) accept Pu / Thorium / MOX (mixed oxide) do not accept uranium-238 or hydrogen (ii) (energy) used to heat water and produce (high pressure) steam the steam drives a turbine (which turns a generator) (b) Neutron(s) shown hitting other U-235 nuclei one uranium nucleus is sufficient U-235 nuclei (splitting) producing 2 or more neutrons (c) any two from: neutrons are absorbed (by boron / control rods) there are fewer neutrons chain reaction slows down / stops accept fewer reactions occur 2 [8] Page 8 of 26 M3. (a) (i) (large) nucleus hit by a neutron splits into (smaller) nuclei and neutron(s) (+ energy) (ii) additional neutrons collide with nuclei causing further fission allow full credit for a correct labelled diagram accept 2 or more neutrons given out at each fission reaction diagram shows 3 discernible sizes, with smaller nuclei and neutrons at same stage (b) cost of (building and) de-commissioning is very high or cost of building is higher accept a correct description of de-commissioning accept high cost to keep the power station safe / secure accept high cost of reprocessing / storage of nuclear waste (c) less pollution from transport carrying the fuel accept coal produces more pollutant gases accept correct named gases accept more radiation pollution from coal than nuclear accept more waste from coal than nuclear do not accept any reference to burning uranium do not accept answers in terms of global warming or acid rain unless developed [5] Page 9 of 26 gains 3 marks M4. (a) it use E = mc 2 mass in kg i.e but each gains mark gains 2 marks evidence of mass in kg (i.e or 0.7/00000) each gains mark squaring the speed of light but (credit alternative ways of stating this) gains 3 marks units J/joule for further mark (N.B credit kj, MJ, GJ but check power of 0 for full credit) 4 (b) (i) idea that the bigger the mass the shorter the life gains mark but idea that decrease in life is much more than proportional to increase in mass or more than proportional to mass 2 gains 2 marks 2 (ii) ideas that: greater mass means greater core temperature/pressure greater core temperature/pressure means greater rate of fusion increase in mass produces a proportionally much greater increase in the rate of fusion each for mark 3 [9] Page 20 of 26 M5. (a) any two from: nuclei / atoms of light elements fuse accept hydrogen or helium for light elements accept join for fuse accept for mark, by nuclear fusion answers about fission negates a mark each (fusion) reaction releases energy / heat / light lots of reactions occur 2 (b) presence of nuclei of the heaviest / heavy / heavier elements accept atom for nuclei (c) (i) (matter / mass) with such a high density / strong gravitational (field) electromagnetic radiation / light is pulled in accept nothing can escape do not accept answers in terms of an empty void (ii) X-rays accept e-m radiation / e-m waves [6] M6. (a) runs out of hydrogen (in its core) accept nuclear fusion slows down do not accept fuel for hydrogen do not accept nuclear fusion stops ignore reference to radiation pressure / unbalanced forces (b) temperature decreases / (relative)luminosity increases as it changes to a red giant if both temperature and luminosity are given both must be correct temperature increases / (relative) luminosity decreases as it changes to a white dwarf if both temperature and luminosity are given both must be correct Page 2 of 26 correct change in temperature and (relative) luminosity as Sun changes to a red giant and then to a white dwarf an answer changes to a red giant and then white dwarf with no mention or an incorrect mention of temperature or (relative) luminosity change gains mark only if no other marks awarded ignore correct or incorrect stages given beyond white dwarf [4] M7. (a) (i) (nuclear) fission accept fision providing clearly not fusion (ii) (released) neutrons are absorbed by further (uranium) nuclei accept hit nuclei for absorbed / hit do not accept atom for nuclei more neutrons are released (when new nuclei split) accept for both marks a correctly drawn diagram (iii) increases by or goes up to 236 (b) any two from: (more) neutrons are absorbed accept there are fewer neutrons (chain) reaction slows down / stops accept keeping the (chain) reaction controlled less energy released accept heat for energy accept gases (from reactor) are not as hot 2 [6] M8. (a) (i) the bigger the masses (of the dust and gases then) the bigger the force / gravity (between them) accept the converse (ii) the greater the distance (between the dust and gases then) the smaller the force / gravity (between them) accept the converse Page 22 of 26 (b) radiation pressure and gravity / gravitational attraction these are balanced / in equilibrium must be in correct context do not accept are equal or there is sufficient / a lot of hydrogen / fuel to last a very long time second mark consequent on first (c) any two from: hydrogen runs out / is used up nuclei larger than helium nuclei formed accept bigger atoms are formed however do not accept any specific mention of an atom with a mass greater than that of iron (star expands to) / become(s) a red giant 2 [6] M9. (a) gravitational attraction accept gravity accept (nuclear) fusion (b) radiation pressure and gravity / gravitational attraction must be in correct context are balanced / in equilibrium accept are equal and opposite do not accept equal or there is sufficient / a lot of hydrogen / fuel do not accept constant supply of hydrogen to last a very long time / for (nuclear) fusion this mark only scores if linked to the supply of hydrogen / fuel reference to burning negates both marks (c) (i) (conversion of) hydrogen to helium accept (conversion of) lighter elements to heavier elements by (nuclear) fusion note do not credit spelling of fusion which could be fission reference to burning negates both marks Page 23 of 26 (ii) massive supply / lots of hydrogen (d) distributed throughout the Universe / space do not accept Solar System for Universe [7] M0. (a) (forces due to) gravity and radiation pressure correct direction of forces (forces) are balanced / equilibrium / equal accept for 3 marks an answer in terms of sufficient hydrogen () to keep fusion reaction () reference to burn / burning negates this mark going at a continuous /steady rate () if fuel is used instead of hydrogen maximum of 2 marks (b) the Sun will remain stable (for several billion years) based on evidence accept a specific example of evidence eg that the Sun has remained stable during the life of our planet / for 4.5 billion years or still contains more than 50 % hydrogen or by comparison with the lifecycle of (similar) stars allow a refutation eg not based on prejudice / whim / hearsay / folk law / historical or religious authority [5] M. (a) fusion do not credit any response which looks like fission of hydrogen / H (atoms) credit only if st mark point scores Page 24 of 26 (b) fusion of other / lighter atoms / elements reference to big bang nullifies both marks during supernova / explosion of star(s) (c) the (available) evidence: supports this idea or does not contradict this idea or can be extrapolated to this idea or (electromagnetic) spectrum from other stars is similar to sun [5] M2. (a) a protostar is at a lower temperature or a protostar does not emit radiation /energy as (nuclear) fusion reactions have not started accept heat or light for energy (b) by (nuclear) fusion accept nuclei fuse (together) nuclear fusion and fission negates this mark of hydrogen to helium elements heavier than iron are formed in a supernova accept a specific example e.g. heavier elements such as gold are formed in a supernova accept heavier elements (up to iron) formed in red giant/red super giant reference to burning (hydrogen) negates the first 2 marks [5] Page 25 of 26 Page 26 of 26
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