Which of these atoms are isotopes of the same element? (2) The process by which nuclei join to form a larger nucleus is called

Transcription

1 Radiation and the Universe Higher Exam revision questions and answers Madeley High School Q. (a) The diagrams represent three atoms, X, Y and Z. Which of these atoms are isotopes of the same element? Give a reason for your answer. (2) (b) In a star, nuclei of atom X join to form nuclei of atom Y. Complete the sentences. The process by which nuclei join to form a larger nucleus is called nuclear.... This is the process by which a star releases.... (2) Page

2 (c) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. A star goes through a lifecycle. Describe the lifecycle of a star like the Sun. (6) (Total 0 marks) Q2. The pie chart shows the sources of the background radiation and the radiation doses that the average person in the UK is exposed to in one year. Radiation dose is measured in millisieverts (msv). (a) (i) What is the total radiation dose that the average person in the UK receives?... Total radiation dose =... msv () Page 2

3 A student looked at the pie chart and then wrote down three statements. Which one of the following statements is a correct conclusion from this data? Put a tick ( ) in the box next to your answer. In the future, more people will be exposed to a greater proportion of radon gas. People that have never had an X-ray get 50% of their radiation dose from radon gas. The radiation dose from natural sources is much greater than from artificial sources. () (b) The concentration of radon gas inside a home can vary from day to day. In some homes, the level can build up to produce a significant health risk. It is estimated that each year 000 to 2000 people die because of the effects of radiation from radon gas. (i) It is not possible to give an exact figure for the number of deaths caused by the effects of radiation from radon gas. Why? () The table gives data for the radiation levels measured in homes in 4 different parts of the UK. The radiation levels were measured using two detectors, one in the living room and one in the bedroom. The measurements were taken over 3 months. Page 3

4 Area of the UK Number of homes in the area Number of homes in the sample Average radiation level in Bq/m 3 Maximum radiation level in Bq/m 3 A B C D Give one reason why the measurements were taken over 3 months using detectors in different rooms () (iii) Use information from the table to suggest why a much higher proportion of homes were sampled in areas C and D than in areas A and B (2) (Total 6 marks) Q3. Some types of food are treated with gamma radiation. Low doses of radiation slow down the ripening of fresh fruit and vegetables while higher doses of radiation kill the bacteria that make the food go off. (a) (i) What is gamma radiation?... () Food packed in crates or boxes can be treated using this method. Why must a source that emits gamma radiation be used? () Page 4

5 (iii) A suitable source of gamma radiation is the isotope caesium 37. Complete the following sentence by choosing the correct word from the box. electrons neutrons protons An atom of caesium 37 has two more... than an atom of caesium 35. () (b) The diagram shows how a conveyor belt can be used to move food past the radioactive source. (i) How do the concrete walls reduce the radiation hazard to workers outside the food treatment area? () Page 5

6 Suggest one way that the dose of radiation received by the food could be increased other than by changing the radioactive source () (c) Some people may not like the idea of eating food treated with radiation. (i) What evidence could a food scientist produce to show that food treated with radiation is safe to eat? (2) The diagram shows the sign displayed on food treated with radiation. Why is it important for people to know which foods have been treated with radiation? () (Total 8 marks) Page 6

7 Q4. (a) The graph shows how the count rate from a sample containing the radioactive substance cobalt-60 changes with time. (i) What is the range of the count rate shown on the graph? From... counts per second to... counts per second. () How many years does it take for the count rate to fall from 200 counts per second to 00 counts per second? Time =... years () (iii) What is the half-life of cobalt-60? Half-life =... years () Page 7

8 (b) The gamma radiation emitted from a source of cobalt-60 can be used to kill the bacteria on fresh, cooked and frozen foods. Killing the bacteria reduces the risk of food poisoning. The diagram shows how a conveyor belt can be used to move food past a cobalt-60 source. (i) Which one of the following gives a way of increasing the amount of gamma radiation the food receives? Put a tick ( ) in the box next to your answer. Increase the temperature of the cobalt-60 source. Make the conveyor belt move more slowly. Move the cobalt-60 source away from the conveyor belt. () To protect people from the harmful effects of the gamma radiation, the cobalt-60 source has thick metal shielding. Which one of the following metals should be used? Draw a ring around your answer. aluminium copper lead () Page 8

9 (c) A scientist has compared the vitamin content of food exposed to gamma radiation with food that has not been exposed. The table gives the data the scientist obtained when she tested kg of cooked chicken. Vitamin Food not exposed to gamma radiation Mass in milligrams Food exposed to gamma radiation Mass in milligrams B B E Niacin Riboflavin Considering only this data, which one of the following is a correct conclusion? Put a tick ( ) in the box next to your answer. Vitamin content is not affected by gamma radiation. Gamma radiation completely destroys some types of vitamin. Exposure increased the content of some types of vitamin. () (Total 6 marks) Page 9

10 Q5. The diagram shows how the thickness of aluminium foil is controlled. The thicker the aluminium foil, the more radiation it absorbs. (a) The designers used a beta radiation source for this control system. (i) Why would an alpha radiation source be unsuitable in this control system? () Why would a gamma radiation source be unsuitable in this control system? () (b) The substance used in the beta radiation source is radioactive. (i) Why are some atoms radioactive? () Explain why radiation is dangerous to humans (2) (Total 5 marks) Page 0

11 Q6. In the early part of the 20th century scientists used the plum pudding model to explain the structure of the atom. (a) What did scientists think that the pudding part of the atom was? () (b) The scientists Geiger and Marsden devised an experiment to test the plum pudding model. They fired positively charged alpha particles at a very thin sheet of gold foil. They then measured the different paths taken by the alpha particles. Page

12 List A gives some of the observations from the experiment. List B gives the conclusions reached from the observations. Draw one line from each observation in List A to the conclusion reached in List B. List A Observation List B Conclusion (2) (c) Following the work of Geiger and Marsden, the plum pudding model of the atom was replaced by the nuclear model of the atom. Explain why it is sometimes necessary for scientists to replace a scientific model. (2) (Total 5 marks) Q7. (a) The chart gives the number of protons and neutrons within the nuclei of 7 different atoms, A G. Page 2

13 Which of these atoms are isotopes of the same element? Give a reason for your answer. (2) (b) Radium-226 is a radioactive isotope that decays into radon gas by emitting alpha particles. The decay can be represented by the equation below. (i) Complete the equation by writing the correct number in each of the boxes. (2) A sample of radium-226 has a count rate of 400 counts per second. The half-life of radium-226 is 600 years. How long will it be before the count rate has fallen to 50 counts per second? Show clearly how you work out your answer.... Page 3

14 Madeley High School Length of time =... years (2) (c) In 927, a group of women who had been employed to paint watch faces with a luminous paint sued their former employer over the illnesses caused by the paint. The women had been told that the paint, which contained radium, was harmless. The company owners and the scientists working for the company knew that radium was harmful and took precautions to protect themselves from the radiation. The women were given no protection. What important issue did the treatment of the women by the company owners and scientists raise? Draw a ring around your answer. economic environmental ethical social Give a reason for your answer. (2) (d) In the 920s, many people, including doctors, thought that radium could be used as a treatment for a wide range of illnesses. Medical records that suggested radium could be harmful were generally ignored. When some of the women who had used the luminous paint died, their deaths were not blamed on radium. Suggest a reason why the evidence suggesting that radium was harmful was generally ignored. () (Total 9 marks) Page 4

15 Q8. (a) The graph shows how a sample of barium-43, a radioactive isotope with a short half-life, decays with time. (i) What is meant by the term isotope?.... () What is meant by the term half-life?.... () Page 5

16 (iii) Use the graph to find the half-life of barium-43. Half-life =... seconds Madeley High School () (b) Humans take in the radioactive isotope carbon-4 from their food. After their death, the proportion of carbon-4 in their bones can be used to tell how long it is since they died. Carbon-4 has a half-life of 5700 years. (i) A bone in a living human contains 80 units of carbon-4. An identical bone taken from a skeleton found in an ancient burial ground contains 5 units of carbon-4. Calculate the age of the skeleton. Show clearly how you work out your answer Age of skeleton =... years (2) Why is carbon-4 unsuitable for dating a skeleton believed to be about 50 years old? () (Total 6 marks) Page 6

17 M. (a) Y and Z both required, either order same number of protons (b) fusion correct order only energy (c) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. No relevant content. 0 marks There is a brief description of the life cycle of a star like the sun. Level ( 2 marks) There is some description of the life cycle of a star like the sun. Level 2 (3 4 marks) There is a clear and detailed description of the life cycle of a star like the sun. Level 3 (5 6 marks) examples of the physics points made in the response to score full marks either the term red giant or white dwarf must be used gases and dust pulled together by gravity nuclear fusion begins when forces are balanced star is stable expands cools becomes a red giant do not accept red supergiant Page 7

18 shrinks Madeley High School temperature rises glows much brighter becomes a white dwarf any mention of supernova negates a mark any mention of black hole negates a mark individual points must be linked in a correct sequence [0] M2. (a) (i) 2.5 The radiation dose from natural sources is much greater than from artificial sources. (b) (i) other factors may be involved accept a specific suggestion eg they may be exposed to other types of radiation accept cannot be sure (in many cases) that the cause of death is radon (poisoning) any one from: different concentrations in different rooms to average out daily fluctuations accept to find an average accept to make the result (more) reliable / valid do not accept to make more accurate on its own (iii) average level (much) higher (in C and D) accept converse Page 8

19 some homes have very high level (in C and D) accept maximum level in A and B is low ormaximum level in some homes (in C and D) is very high accept higher radiation levels (in C and D) for mark [6] M3. (a) (i) electromagnetic (wave / radiation) accept em (wave / radiation) ignore reference to frequency (iii) gamma can penetrate the crate / box / packaging accept converse (but must relate to both alpha and beta) ignore just gamma radiation kills bacteria accept can get through to food neutrons (b) (i) absorb gamma / radiation accept it stops / reduces the radiation any one from: slow down the conveyor belt food does more than one circuit stay on the conveyor belt longer food closer to the source / radiation ignore larger doses / use more of the source ignore thinner packaging (c) (i) idea of testing food on humans / animals Page 9

20 no (measured) ill effects or monitor their health accept monitor people that have eaten the food accept a measurement / comparison for mark eg measure the amount of radiation in treated food comparison plus a reason for the comparison would get 2 marks eg idea of measuring level of radiation in treated food with no measurable increase in level = 2 marks or comparing it to untreated food = 2 marks so can make own decision about eating or not eating treated food accept may be against their religious / moral views accept some people prefer food that hasn t been tampered with ignore in case they don t like the idea of eating treated food accept don t want to eat treated food ignore might be allergic to the food eg think it will give them cancer = 0 marks think it will give you cancer so I need to know so that I can choose = mark [8] M4. (a) (i) 200 to 50 accept either order 5.3 accept values between 5.2 and 5.4 inclusive (iii) 5.3 accept values between 5.2 and 5.4 inclusive ortheir (a) (b) (i) Make the conveyor belt move more slowly Page 20

21 lead (c) Exposure increased the content of some types of vitamin. [6] M5. (a) (i) cannot penetrate aluminium allow can only pass through air / paper too weak is neutral gamma rays not affected (by aluminium) allow all / most (gamma rays) to pass through too strong is neutral danger is neutral (b) (i) (nuclei) unstable causes harm / damage to body / cells allow radiation sickness detail e.g., causes mutations / causes cancer / damages DNA / damages chromosomes allow two effects for 2 marks [5] M6. (a) (mass of) positive charge Page 2

22 (b) three lines correct allow mark for correct line if more than line is drawn from a box in List A then all those lines are incorrect 2 (c) new scientific evidence / data is obtained which cannot be explained by the model [5] M7. (a) B E G all 3 required and no other any order same number of / 88 protons (and different numbers of neutrons) same number of electrons is insufficient Page 22

23 (b) (i) 222 Madeley High School allow mark for obtaining 3 half-lives 2 (c) ethical deceived / lied to (about safety of working conditions) accept (women) not warned of the dangers given no protection is insufficient or value own / scientists' lives more than womenor did not treat women humanely (d) accept any sensible suggestion eg too many interests in continued use of radium evidence may cause public unrest do not accept not enough evidence doctors not want to be blamed for illnesses (caused by radium) accept doctors not wanting to be sued (for harm caused by using radium) doctors thought (possible) benefits outweighed (possible) risks do not accept did not know radium could be harmful believe radium could treat illnesses is insufficient [9] Page 23

24 M8. (a) (i) element with equal number of protons, different number neutrons or same atomic/proton number different mass/nuclear number Madeley High School time taken for activity or count rate or number of nuclei to decrease to half accept parents atoms or radioactive isotope do not accept time taken for radioactivity/substance/ material to halve (iii) 2 (s) (b) (i) (years) allow mark for iterative steps or statement of 4 half-lives 2 decay (of carbon 4) over 50 years is insignificant accept very little decay accept change is too small [6] Page 24