The nuclear model of the atom — Paper 3 · IGCSE Physics 0625

11 Fig. 11.1 shows the paths of three α-particles moving towards a thin gold foil. gold foil A B C Fig. 11.1 Particle A is moving directly towards a gold nucleus. Particle B is moving along a line which passes close to a gold nucleus. Particle C is moving along a line which does not pass close to a gold nucleus. (a) On Fig. 11.1, complete the paths of the α-particles A, B and C. [3] (b) State how the results of such an experiment, using large numbers of α-particles, provides evidence for the existence of nuclei in gold atoms. … … … … [3] [Total: 12]

6 marks

Mark scheme: 11 (a) A doubles back, either side B1 B carries on, slightly deflected B1 C carries straight on B1 [3] (b) only (very) few scattered through large angles B1 most pass undeviated so most of atom space B1 scattering/deflection/repulsion due to concentrated mass/charge/charge/nucleus B1 [3] [Total: 6]

This question in 0625/31 May/June 2007

10 A certain element is known to exist as two different isotopes. For Examiner’s (a) State one thing that is the same for atoms of both isotopes. Use … [1] (b) State one thing that is different between atoms of these two isotopes. … [1] (c) An atom of one of these isotopes is unstable and decays into a different element by emitting a -particle. (i) State one thing about the atom that remains the same during this decay. … [1] (ii) State one thing about the atom that changes as a result of this decay. … [1] [Total: 4]

4 marks

Mark scheme: 10 (a) proton number OR atomic number OR (number of) protons / electrons OR position in periodic table OR chemical properties B1 (b) mass (number) OR nucleon number OR (number of) neutrons / nucleons OR (number of) protons plus (number of) neutrons B1 (c) (i) mass (number) OR nucleon number OR (number of) nucleons OR (number of) protons plus (number of) neutrons B1 (ii) proton number OR atomic number OR (number of) neutrons OR (number of) protons / neutrons / electrons OR position in periodic table OR chemical properties OR a neutron changes into a proton B1 [4]

This question in 0625/31 May/June 2010

10 In Geiger and Marsden’s α-particle scattering experiment, α-particles were directed at a very thin gold foil. Fig. 10.1 shows five of the nuclei of the atoms in one layer in the gold foil. Also shown are the paths of three α-particles directed at the foil. Fig. 10.1 (a) On Fig.10.1, complete the paths of the three α-particles. [3] (b) (i) What result of the experiment confirmed that an atom consisted of a very tiny charged core, containing almost all the mass of the atom? … … [1] (ii) What is the sign of the charge on this core? … [1] (iii) What occupies the space between these charged cores? … [1] [Total: 6]

6 marks

Mark scheme: 10 (a) top bent down to R of layer B1 middle straight on B1 bottom deflected back to left B1 for all 3 ignore subsequent curving away from layer of nuclei (b) (i) deflection > 90°/the bottom one B1 (ii) positive ignore numbers B1 (iii) nothing/vacuum/space/electrons B1 [Total: 6]

This question in 0625/32 Oct/Nov 2010

11 An atom of one of the isotopes of sodium contains 11 protons, 11 electrons and 13 neutrons. (a) Underline which of these three will be the same in neutral atoms of all isotopes of sodium. [2] (b) State the nucleon number of this isotope. … [1] (c) What can you say about the chemical properties of the different isotopes of sodium? … [1] (d) One isotope of sodium is 25Na. How many neutrons are there in one atom of this isotope? … [1] [Total: 5]

5 marks

Mark scheme: 11 (a) 11 protons, 11 electrons -1 e.e.o.o. B2 (b) 24 B1 (c) same/identical ignore (very) similar B1 (d) 14 B1 [Total: 5]

This question in 0625/32 Oct/Nov 2010

6 (a) Six different nuclides have nucleon and proton numbers as follows: nuclide nucleon number proton number A 214 84 B 214 85 C 211 84 D 211 86 E 210 82 F 210 83 State which two nuclides are isotopes of the same element. … and … [1] (b) Thorium-232 has a half-life of 1.4 × 1010 years. At a particular instant, the activity of a sample of thorium-232 is 120 Bq. (i) Calculate the time taken for the activity of this sample to fall to 15 Bq. time taken … [1] (ii) Explain why, when the activity has become 15 Bq, much of the sample will no longer be thorium-232. … … … [1] (iii) The sample of thorium-232 is used in an experiment in a laboratory. Explain why its activity may be regarded as constant. … … … [1] [Total: 4]

4 marks

Mark scheme: 6 (a) A and C B1 (b) (i) 4.2 × 1010 years B1 (ii) idea of decay OR changes proton/neutron/nucleon number OR change into another nuclide/isotope/element/type of atom OR emits α/β particle (ignore γ / radiation) B1 (iii) idea of insignificant change in activity during stated time up to 5 × 109 years OR experiment time insignificant c.f. 1.4 × 1010 years OR long half life OR long time to decay B1 [4] IGCSE – May/June 2011 0625 31

This question in 0625/31 May/June 2011

11 (a) An atom consists of a nucleus made up of protons and neutrons, surrounded by orbiting electrons. (i) Which of these particles has a positive charge? … [1] (ii) Which two of these particles have almost equal mass? … and … [1] 107 (b) A silver nucleus is denoted by Ag. State the number of protons and the number of neutrons 47 in this nucleus. number of protons = … number of neutrons = … [2] (c) The graph in Fig. 11.1 shows part of the decay curve of a radioactive nuclide. The count rate is plotted against time. 300 count rate counts / s 200 100 0 0 5 10 15 20 25 30 time / hours Fig. 11.1 (i) Use the graph to find the half-life of this nuclide. half-life = … [1] (ii) Plot two more points on Fig. 11.1 at times greater than 10 hours. Use a dot in a circle to indicate each point. [2] [Total: 7]

7 marks

Mark scheme: 11 (a) (i) proton B1 (ii) proton and neutron B1 (b) number of protons = 47 B1 number of neutrons = 60 B1 (c) (i) 8 hrs +/– 0.25 hrs B1 (ii) first point plotted is half the count-rate of a point on the curve, and 8 hours after that point (ecf from (c)(i) ) B1 second point plotted same as above or with respect to first point plotted B1 possible points include: 16 hrs, 80 counts/s 24 hrs, 40 counts/s 13.5 hrs, 100 counts/s 21.5 hrs, 50 counts/s 16.5 hrs, 75 counts/s [7]

This question in 0625/32 May/June 2011

11 (a) An atom consists of a nucleus made up of protons and neutrons, surrounded by orbiting electrons. (i) Which of these particles has a positive charge? … [1] (ii) Which two of these particles have almost equal mass? … and … [1] 107 (b) A silver nucleus is denoted by Ag. State the number of protons and the number of neutrons 47 in this nucleus. number of protons = … number of neutrons = … [2] (c) The graph in Fig. 11.1 shows part of the decay curve of a radioactive nuclide. The count rate is plotted against time. 300 count rate counts / s 200 100 0 0 5 10 15 20 25 30 time / hours Fig. 11.1 (i) Use the graph to find the half-life of this nuclide. half-life = … [1] (ii) Plot two more points on Fig. 11.1 at times greater than 10 hours. Use a dot in a circle to indicate each point. [2] [Total: 7]

7 marks

Mark scheme: 11 (a) (i) proton B1 (ii) proton and neutron B1 (b) number of protons = 47 B1 number of neutrons = 60 B1 (c) (i) 8 hrs +/– 0.25 hrs B1 (ii) first point plotted is half the count-rate of a point on the curve, and 8 hours after that point (ecf from (c)(i) ) B1 second point plotted same as above or with respect to first point plotted B1 possible points include: 16 hrs, 80 counts/s 24 hrs, 40 counts/s 13.5 hrs, 100 counts/s 21.5 hrs, 50 counts/s 16.5 hrs, 75 counts/s [7]

This question in 0625/33 May/June 2011

12 The most abundant stable isotope of strontium is strontium-88. Its nucleon number is 88 and its proton number is 38. In nuclide notation it is written xySr. (a) Write down (i) the values of x and y for strontium-88, x = … y = … (ii) the number of neutrons in a nucleus of strontium-88, … (iii) the number of electrons in a neutral atom of strontium-88. … [3] (b) Strontium-90 is a radioactive isotope produced by nuclear reactions. State how the structure of this isotope differs from that of strontium-88. … … … … … [2] [Total: 5]

5 marks

Mark scheme: 12 (a) (i) x = 88 AND y = 38 B1 (ii) 50 B1 (iii) 38 B1 [3] (b) different numbers of neutrons / nucleons NOT different no of protons / electrons C1 (strontium-90 has) 52 neutrons / 90 nucleons OR 2 more neutrons / nucleons A1 [2]

This question in 0625/32 Oct/Nov 2011

11 (a) Complete the following statements. For Examiner’s (i) An α-particle consists of … . Use (ii) A β-particle consists of … . [3] (b) As α-particles and β-particles pass through a gas, molecules of the gas become ionised. Explain what is meant by the ionisation of a gas molecule. … … [1] (c) Fig. 11.1 shows a beam of α-particles and a beam of β-particles in a vacuum. The beams are about to enter a region in which a very strong magnetic field is acting. The direction of the magnetic field is into the page. _-particles `-particles uniform magnetic field Fig. 11.1 (i) Suggest why the paths of the particles in the magnetic field are curved. … [1] (ii) Sketch the paths of both types of particle in the magnetic field. [3] [Total: 8]

8 marks

Mark scheme: 11 (a) (i) 2 protons B1 2 neutrons B1 (ii) a (fast moving) electron B1 (b) electron/electrons removed from/gained by the molecule B1 (c) (i) force because particle is charged OR the force on the particles is perpendicular to their paths OR direction of force changes as direction of motion changes B1 (ii) α-particle curve up the page in at least half of width of field B1 β-particle curve opposite to α-particle curve OR down page if α line has no B1 curvature anywhere smaller radius of β path clear B1 [Total 8]

This question in 0625/31 May/June 2013

10 There are two stable, naturally occurring isotopes of hydrogen. For Examiner’s Common hydrogen (hydrogen-1) has a proton number of 1 and a nucleon number of 1. Use Hydrogen-2 (deuterium) has a nucleon number of 2. There is also a radioactive isotope of hydrogen called tritium (hydrogen-3), with a nucleon number of 3. (a) Complete the table for neutral atoms of these isotopes. hydrogen-1 hydrogen-2 hydrogen-3 (deuterium) (tritium) number of protons number of neutrons number of electrons [3] (b) Two samples of tritium are stored in aluminium containers of different thickness. Sample 1 is in a container of thickness 0.5 mm and radiation can be detected coming through the container. Sample 2 is in a container of thickness 5 mm and no radiation comes through. (i) State the type of radiation coming through the container of Sample 1. … [1] (ii) Explain your answer to (b)(i). … … … … [2] (c) Under conditions of extremely high temperature and pressure, as in the interior of the Sun, hydrogen nuclei can join together. (i) Name this process. … [1] (ii) State whether energy is released, absorbed or neither released nor absorbed during this reaction. … [1] (d) When a nucleus of a certain isotope of uranium is bombarded by a suitable neutron, it For splits into two smaller nuclei and energy is released. Examiner’s Use Name this process. … [1] [Total: 9] Turn over for Question 11

9 marks

Mark scheme: 10 (a) hydrogen-1 deuterium tritium no.of protons 1 1 1 no. of 0 1 2 neutrons no. of 1 1 1 electrons proton line correct B1 neutron line correct, do not accept blank for 0 B1 electron line correct B1 [3] (b) ignore any reference to background radiation throughout this part (i) beta / fast moving electrons B1 [1] (ii) any two from: beta stopped by 5 mm/thick Al / beta not stopped by 0.5 mm/thin Al B1 alpha stopped by 0.5mm/thin Al accept stopped by paper B1 [2] gamma not stopped by 5 mm or more/thick Al ignore any reference to range in air (c) (i) fusion / thermonuclear (reaction) B1 [1] (ii) (energy) released B1 [1] (d) fission B1 [1] [Total: 9] IGCSE – May/June 2013 0625 32

This question in 0625/32 May/June 2013

9 In a laboratory experiment, the isotope uranium-238 is used as a source of α-particles. For Examiner’s (a) State Use (i) one feature of uranium-238 nuclei that is the same for the nuclei of other uranium isotopes, … [1] (ii) one feature of uranium-238 nuclei that is different for the nuclei of other uranium isotopes. … [1] (b) Fig. 9.1 shows the α-particles from the uranium source being directed at a very thin gold foil, in a vacuum. thin gold foil moveable _-particle detector uranium source vacuum _-particles Fig. 9.1 To investigate the scattering of α-particles, a detector is moved to different positions around the very thin gold foil and measurements are recorded. Describe the results from this scattering experiment and explain what they show about the structure of atoms. … … … … … … … [4] [Total: 6]

6 marks

Mark scheme: 9 (a) (i) same number of / 92 protons (in nucleus) (IGNORE electrons) B1 (ii) different number of neutrons B1 (b) most α-particles travel straight (through the foil) M1 nucleus small / atom mostly empty space A1 small number deflected (through large angles) M1 most of mass in nucleus ACCEPT nucleus positive/charged A1 [6]

This question in 0625/33 May/June 2013

11 Strontium-90 is a radioactive isotope that emits β-particles as it decays. The nuclear equation For below shows this decay. Examiner’s Use 90 a 0 38Sr b X + –1e (a) Calculate (i) the value of a, a = … (ii) the value of b. b = … [2] (b) (i) Tick the element from the list below that is produced by this decay. element proton number place one tick in this column selenium 34 bromine 35 krypton 36 rubidium 37 strontium 38 yttrium 39 zirconium 40 niobium 41 molybdenum 42 [1] a (ii) The isotope X is also radioactive and undergoes β-decay. b State the name of the element that is produced by this decay. … [1] Question 11 continues on the next page. (c) Three nuclei are represented as For 83 209 84 Examiner’s 42X 83Y 42Z Use State and explain which nuclei are isotopes of the same element. … … … … [2] [Total: 6]

6 marks

Mark scheme: 11 (a) (i) 90 B1 (ii) 39 B1 [2] (b) (i) tick corresponds to candidate’s (a)(ii) B1 [1] (ii) zirconium c.a.o. B1 [1] (c) X (and) Z (are isotopes of same element) M1 same proton number A1 [2] [Total: 6]

This question in 0625/32 Oct/Nov 2013

11 In a famous experiment, a beam consisting of a very large number of α-particles was projected, in a vacuum, at a very thin gold foil. Fig. 11.1 shows the paths of three of the α-particles A, B and C travelling towards the foil. gold foil A B C Fig. 11.1 α-particle A is travelling along a line which does not pass very close to a gold nucleus. α-particle B is travelling along a line which passes close to a gold nucleus. α-particle C is travelling directly towards a gold nucleus. (a) Explain why an α-particle and a gold nucleus repel each other. … [1] (b) On Fig. 11.1, draw lines with arrows to show the continuation of the paths of α-particles A, B and C. [3] (c) State two conclusions, about gold atoms, which resulted from the experiment. … … … … [2] [Total: 6]

6 marks

Mark scheme: 11 (a) Both have positive/same charge B1 (b) A continues along original line B1 B deflected by any angle up to 135° (by eye) B1 C returns along same line OR deflected more than 135° (by eye) B1 (c) Any two from: B2 Atom is mostly empty space OR Nucleus is (very) much smaller than the atom OR Nucleus is very small Charge of nucleus is (very) concentrated / (very) dense OR Nucleus contains all the positive charge of the atom OR Nucleus has positive charge Nucleus contains most of the mass of the atom OR Nucleus is (very) massive OR Nucleus is (very) dense [Total: 6]

This question in 0625/32 Feb/March 2015

10 (a) State the nature of an α-particle. … … [1] (b) Describe how an electric field between two charged plates could be used to determine whether a beam of particles consists of α- or β-particles. … … … [2] (c) Describe the path of γ-rays in a magnetic field. … … [1] (d) State what is meant by the term isotopes. Use the terms proton number and nucleon number in your explanation. … … … … … [3] [Total: 7]

7 marks

Mark scheme: 10 (a) 2 protons and 2 neutrons OR helium nucleus B1 (b) α in direction of field OR α towards negative (plate) OR β in opposite direction to field OR β towards positive (plate) OR α and β deflected in opposite directions C1 α in direction of field OR α towards negative (plate) AND β in opposite direction to field OR β towards positive (plate) A1 (c) not deflected B1 (d) versions owtte of same element owtte B1 (isotopes of same element have) same proton number/number of protons/atomic number/Z B1 (isotopes of same element have) different nucleon numbers/ number of neutrons/mass number/A B1

This question in 0625/32 May/June 2015

9 An extremely violent nuclear reaction is taking place at the centre of the Sun. It is this reaction that enables the Sun to emit both a very large quantity of energy and an extremely large number of charged particles. (a) Name the type of nuclear reaction taking place in the Sun. … [1] (b) Many of the charged particles produced by the Sun are emitted from its surface at high speeds and travel out into space. (i) Explain why these particles constitute an electric current. … … [1] (ii) State the equation that relates the electric current I to the charge Q that is flowing. Define any other terms in the equation. … … [1] (c) Some of the particles emitted by the Sun travel straight towards the Earth until they enter the Earth’s magnetic field. Because they constitute a current, they experience a force and are deflected. (i) Describe the relationship between the direction of the force and 1. the direction of the current, … [1] 2. the direction of the magnetic field. … [1] (ii) A negatively charged particle is travelling in a magnetic field. This is represented in Fig. 9.1. The direction of the magnetic field is into the page. direction of travel of particle magnetic field into page negative particle Fig. 9.1 On Fig. 9.1, draw an arrow, labelled F, to show the direction of the force that acts on the particle. [1] [Total: 6]

6 marks

Mark scheme: 9 (a) (nuclear) fusion B1 (b) (i) charges are moving (and current is the (rate of) flow of charge) B1 (ii) Q = It AND t is time B1 (c) (i) 1. (they are) perpendicular OR at right angles OR at 90° B1 2. (they are) perpendicular OR at right angles OR at 90° B1 (ii) arrow (labelled F) perpendicular to direction AND pointing towards the bottom right of the page B1 [Total: 6]

This question in 0625/33 May/June 2015

11 (a) State, in terms of the particles in each nucleus, how the nuclei of two isotopes of the same element are different. … [1] (b) Fig. 11.1 shows a graph of nucleon number against proton number. The nucleus 21 2 Bi is 8 3 plotted on the graph at the cross marked P. 213 P 212 nucleon 211 number 210 209 208 79 80 81 82 83 84 proton number Fig. 11.1 (i) On Fig. 11.1, 1. plot a cross labelled Q for the nucleus formed when the 21 2 Bi nucleus emits an 8 3 α-particle, 2. plot a cross labelled R for the nucleus formed when the 21 2 Bi nucleus emits a 8 3 β-particle. [4] (ii) The half-life for the decay of 21 2 Bi is 60 minutes. 8 3 A sample of 21 2 Bi is placed at a fixed distance from a detector. The initial measurement 8 3 of the count rate from the sample of 21 2 Bi is 2400 counts per minute. 8 3 Calculate the count rate from the sample 5.0 hours later. count-rate = … [2] [Total: 7]

7 marks

Mark scheme: 11 (a) different number of neutrons (in the nucleus) OR different neutron number B1 (b) (i) 1 letter Q at nucleon number = 208 B1 proton number = 81 B1 2 letter R at nucleon number = 212 B1 proton number = 84 B1 (ii) evidence of dividing original number by 2 C1 75 (counts) / min OR 1.25 (counts) / s OR 4500 (counts) / hr A1 [Total: 7]

This question in 0625/31 Oct/Nov 2015

11 Uranium-238 and uranium-234 are radioactive isotopes of the element uranium. A uranium-238 nucleus is different from a uranium-234 nucleus but both decay by the emission of an α-particle. (a) (i) In terms of the particles in each, state how a nucleus of uranium-238 differs from a nucleus of uranium-234. … … [2] (ii) Although the two nuclei are different, they are both nuclei of uranium. State a property that makes these isotopes the same element. … … [1] (b) When α-particles pass through air, they are more strongly ionising than β-particles. Suggest two reasons why this is so. … … [2] (c) In an experiment, α-particles are allowed to strike a thin gold foil in a vacuum. Almost all the α-particles pass straight through the gold undeflected. Only a very small number of α-particles are deflected from their original path. This result reveals certain features of the atoms of the gold. State what is shown about atoms by the fact that (i) most α-particles pass straight through the gold undeflected, … … [1] (ii) some α-particles are deflected back the way they came. … … [1] [Total: 7]

7 marks

Mark scheme: 11 (a) (i) number of / more neutrons B1 4 more neutrons B1 (ii) same number of protons / proton number / atomic number / chemical reactions / number of electrons (in neutral atom) B1 (b) any two lines from: larger charge slower moving more massive greater volume / more chance of collision more energy B2 (c) (i) atom is mostly empty space OR nucleus very small OR mass concentrated at centre / nucleus OR greater distance between nuclei B1 (ii) charge concentrated at centre / nucleus B1 [Total: 7]

This question in 0625/33 Oct/Nov 2015

11 (a) Any atomic nucleus can be represented as AZX. (i) State which letter, A, X or Z, is the • chemical symbol, … • nucleon number, … • proton number. … [2] (ii) A nucleus of americium-241 can be written as 24195Am. 1. Determine the number of electrons in a neutral atom of americium-241. number of electrons = … [1] 2. Determine the number of neutrons in a nucleus of americium-241. number of neutrons = … [1] (b) Explain what is meant by isotopes of an element. … … … … [2] [Total: 6]

6 marks

Mark scheme: 11(a)(i) (chemical symbol): X (nucleon number): A (proton number): Z any two for one mark B2 11(a)(ii) 1. 95 2. 146 B1 B1 11(b) same number of protons (in nucleus) different numbers of neutrons (in nucleus) B1 B1 Total: 6

This question in 0625/32 May/June 2016

11 (a) Any atomic nucleus can be represented as AZX. (i) State which letter, A, X or Z, is the • chemical symbol, … • nucleon number, … • proton number. … [2] (ii) A nucleus of americium-241 can be written as 24195Am. 1. Determine the number of electrons in a neutral atom of americium-241. number of electrons = … [1] 2. Determine the number of neutrons in a nucleus of americium-241. number of neutrons = … [1] (b) Explain what is meant by isotopes of an element. … … … … [2] [Total: 6]

6 marks

Mark scheme: 11(a)(i) (chemical symbol): X (nucleon number): A (proton number): Z any two for one mark B2 11(a)(ii) 1. 95 2. 146 B1 B1 11(b) same number of protons (in nucleus) different numbers of neutrons (in nucleus) B1 B1 Total: 6

This question in 0625/33 May/June 2016

10 This question is about atoms. (a) Complete the sentences below with the correct type of particle in each case. • In a neutral atom, the nucleus is surrounded by negative … . • The nucleus is made up of positive … and neutral … . [2] (b) Explain the meaning of the term isotope. … … … [1] (c) α-particles, β-particles and γ-rays may be emitted from radioactive nuclei. Complete the table. Place one tick (✓) in each column. negatively charged most ionising most penetrating α-particle β-particle γ-rays [3] [Total: 6]

6 marks

Mark scheme: 10(a) electrons B1 protons AND neutrons B1 10(b) same number of protons OR proton number AND different number of nucleons OR neutrons/nucleon number B1 10(c) alpha – most ionising B1 beta – carries a negative charge B1 gamma – most penetrating B1 Total: 6

This question in 0625/33 Oct/Nov 2016

12 This question is about the structure of an atom. (a) An atom contains three types of particle. Complete the table with the name of each type of particle. particle charge 0 +1 –1 [3] (b) Draw a labelled diagram to show the structure of a lithium atom, 73Li. [4] [Total: 7]

7 marks

Mark scheme: 12(a) neutron B1 proton B1 electron B1 12(b) nucleus labelled B1 P + N in central position B1 3 protons and 4 neutrons clearly shown B1 3 electrons in outer shell(s) B1 Total: 7

This question in 0625/32 Feb/March 2017

8 Iodine-131 is a radioactive isotope of iodine. Iodine-131 decays by the emission of a β-particle and a γ-ray. (a) A nucleus of iodine-131 can be represented as 13153I Determine the number of neutrons in a nucleus of iodine-131. number of neutrons … [1] (b) β-particles and γ-rays are ionising radiations. Explain the meaning of ionising radiations. … … [1] (c) Fig. 8.1 shows a decay curve for iodine-131. 32 000 count rate counts / minute 28 000 24 000 20 000 16 000 12 000 8000 4000 0 0 4 8 12 16 20 24 28 32 36 40 time / days Fig. 8.1 Use information from Fig. 8.1 to determine the half-life of iodine-131. Show clearly how you used the graph. half-life = … days [3] (d) A different radioactive substance has a half-life of 120 hours. Calculate the time for it to decay to 25% of its original amount. time = … hours [2] [Total: 7]

7 marks

Mark scheme: 8(a) 78 B1 8(b) (radiations that ) remove electrons OR break molecules B1 8(c) pair of count-rate values used C1 clear indication of use of graph, expect two vertical lines or two clear indications on axes using their values C1 8 days (± 1 day) A1 8(d) 2 half-lives C1 240 hours A1 Total: 7

This question in 0625/31 May/June 2017

12 Fig. 12.1 represents the particles in an atom of the element lithium. neutron X Fig. 12.1 (not to scale) (a) (i) State the name of particle X. … [1] (ii) State the charge of particle X. … [1] (iii) Tick one box in Fig. 12.2 that correctly represents an isotope of lithium. Fig. 12.2 [1] (b) A sample of lithium contains 1.00 mg of a radioactive isotope of lithium. Calculate the mass of the isotope that remains after 2 half-lives. mass = … mg [2] [Total: 5]

5 marks

Mark scheme: 12(a) proton B1 positive or +1 B1 12(a)(ii) tick in third box B1 12(b) idea of mass being halved, e.g. 0.5 C1 0.25 (mg) A1 Total: 5

This question in 0625/32 May/June 2017

12 (a) A scientist has a sample of a radioactive substance. Suggest how he can determine whether the sample is emitting α-particles and whether it is emitting β-particles. … … … … … … … … … … [4] (b) The table lists the charge and location of particles in an atom. Complete the table by stating the charge and the location for each type of particle in an atom. particle charge location electron negative neutron proton in the nucleus [3] [Total: 7]

7 marks

Mark scheme: 12(a) Any 4 from: type of detector named e.g. Geiger counter place absorber between sample and detector and measure count rate uses paper to absorb/stop alpha particles if count rate or radiation decreases/is stopped/is absorbed returns to background sample is emitting alpha particles OR if count rate remains unchanged sample is emitting beta particles uses aluminium to absorb/stop alpha particles if count rate or radiation decreases/is stopped/is absorbed returns to background sample is emitting beta particles B4 12(b) particle charge location electron negative outside/orbiting nucleus neutron neutral/zero in the nucleus proton positive in the nucleus B3 Total: 7

This question in 0625/33 May/June 2017

11 A nucleus of polonium-210 can be represented as 21084Po. (a) (i) State the number of protons in a nucleus of polonium-210 … [1] (ii) State the number of neutrons in a nucleus of polonium-210 … [1] (iii) State the number of electrons in a neutral atom of polonium-210 … [1] (b) Polonium-210 is radioactive. When polonium-210 decays it emits alpha radiation. Name two other types of radiation emitted when radioactive elements decay. … and … [1] (c) Polonium-210 has a half-life of 138 days. A sample of polonium-210 has a mass of 0.4 g. Calculate the time for the sample to decay until only 0.1 g of polonium-210 remains. time = … days [3] [Total: 7]

7 marks

Mark scheme: 11(a)(i) 84 B1 11(a)(ii) 126 B1 11(a)(iii) 84 B1 11(b) beta and gamma OR gamma and beta B1 11(c) 0.4 ÷ 2 = 0.2 C1 AND 0.2 ÷ 2 = 0.1 or 2 × 138 C1 276 (days) A1

This question in 0625/31 Oct/Nov 2017

8 (a) An atom of carbon contains protons, neutrons and electrons. Indicate where each particle is found in the atom. Place a tick in the appropriate box. particle in the orbiting the nucleus nucleus electron neutron proton [3] (b) An atom of carbon contains 6 protons, 7 neutrons and 6 electrons. (i) State the proton number of the carbon. … [1] (ii) State the nucleon number of the carbon. … [1] (c) Carbon has many different isotopes. (i) Explain the meaning of the term isotope. … … … [2] (ii) The nuclide notation for the carbon in (b) is 136C. Suggest the nuclide notation for another possible isotope of carbon. … [1] [Total: 8]

8 marks

Mark scheme: 8(a) 1st row tick under orbiting the nucleus B1 2nd row tick under in the nucleus B1 3rd row tick under in the nucleus B1 8(b)(i) 6 B1 8(b)(ii) 13 B1 8(c)(i) same proton / atomic number B1 different nucleon number / number of neutrons / mass number B1 8(c)(ii) any acceptable isotope with proton number of 6 B1

This question in 0625/32 Oct/Nov 2017

10 (a) Fig. 10.1 shows a balloon hanging from an insulating thread. insulating thread balloon Fig. 10.1 (i) A student gives the balloon a positive charge. Which statement explains why the balloon becomes positively charged? Tick one box. The balloon gains electrons The balloon loses electrons The balloon gains protons The balloon loses protons [1] (ii) The student brings a charged rod close to the balloon as shown in Fig. 10.2. + + + + + + + charged + + rod + + + + Fig. 10.2 State the type of charge on the rod. … Explain your answer. … … [2] (b) Electrical charges can move easily through some materials. Draw a circle around each material that charges can move through easily. copper plastic rubber silver wood [1] [Total: 4]

4 marks

Mark scheme: 10(a)(i) second box (The balloon loses electrons) ticked 1 10(a)(ii) positive (charge) 1 like charge(s) repel 1 10(b) circle around copper AND silver 1

This question in 0625/32 May/June 2018

12 (a) Fig. 12.1 shows a diagram to represent a helium atom, and an incomplete key. key proton … … … Fig. 12.1 Complete the key in Fig. 12.1. State the name of each particle. [2] (b) The table in Fig. 12.2 compares two isotopes of helium. 32He 52He number of protons number of neutrons Fig. 12.2 For each isotope, write the number of protons and the number of neutrons in the correct places in the table. [2] (c) The nucleus of the helium atom in (a) is the same as an α-particle. (i) Describe the penetrating ability of α-particles. … … [1] (ii) Explain why it is dangerous to swallow a source that emits α-particles. … … … … [2] [Total: 7]

7 marks

Mark scheme: 12(a) neutron 1 electron 1 12(b) upper row: 2 in both 1 lower row: 1 in left box AND 3 in right box 1 12(c)(i) weak(ly) penetrating 1 12(c)(ii) Any two from: absorbed over a short distance large mass high charge highly ionising cause cell mutation/damage DNA (high risk) of developing cancer 2

This question in 0625/33 May/June 2018

9 A student experiments with electric charge. (a) The student uses a dry cloth to rub a plastic rod. The rod becomes positively charged. Explain how the friction between the rod and the cloth causes the rod to become positively charged. Use your ideas about the movement of charge. … … … [2] (b) The student suspends a balloon from an insulating thread, as shown in Fig. 9.1. insulating thread balloon Fig. 9.1 The balloon has an electric charge. Explain how the student can use a positively charged rod to determine the charge on the balloon. … … … [3] [Total: 5]

5 marks

Mark scheme: 9(a) electrons B1 move / transfer from the rod OR move / transfer to the cloth B1 9(b) Any 3 from: (idea of bringing) rod near balloon if balloon repels it is positively charged as like charges repel B3

This question in 0625/31 Oct/Nov 2018

12 This notation represents the nucleus of a neutral atom of carbon-14. 146C (a) State the number of: 1. protons in the nucleus of an atom of carbon-14 … [1] 2. electrons orbiting the nucleus of an atom of carbon-14 … [1] 3. neutrons in the nucleus of an atom of carbon-14. … [1] (b) Carbon-14 is an isotope of carbon. Carbon-12 is another isotope of carbon. Compare the nucleus of carbon-14 with the nucleus of carbon-12. State the similarities and differences. … … … … … [3] (c) Scientists use carbon-14 to estimate the age of wood that is very old. A very old sample of wood contains 1.0 × 108 carbon-14 atoms. When the sample was new, it contained 8.0 × 108 carbon-14 atoms. The half-life of carbon-14 is 5 700 years. Estimate the age of the sample of wood. age of wood = … years [3]

9 marks

Mark scheme: 12(a) 1. 6 B1 2. 6 B1 3. 8 B1 12(b) Any three from: (nucleus has) same number protons or same atomic / proton number same charge different mass different nucleon number different number of neutrons B3 12(c) idea of 3 half-lives Or 8.0 → 4.0 → 2.0 → 1.0 C1 5700 × 3 C1 17 100 (years) A1

This question in 0625/31 Oct/Nov 2018

12 (a) Draw a line from each part of the atom to its description. part of the atom description is an electromagnetic wave nucleus is the centre of the atom electron has no electric charge neutron orbits the centre of an atom [3] (b) Tritium is an isotope of hydrogen. It can be represented by 3 H. 1 (i) Explain the meaning of the term isotope. … … … [2] (ii) Fig. 12.1 shows how the activity of a sample of tritium varies with time. 18 000 16 000 count rate counts / min 14 000 12 000 10 000 8000 6000 4000 2000 0 0 10 20 30 40 50 60 time / years Fig. 12.1 Use Fig. 12.1 to calculate the half-life of tritium. Show clearly how you used the graph. half-life = … years [3] [Total: 8]

8 marks

Mark scheme: 12(a) line from ‘nucleus’ to ‘is the centre of an atom’ B1 line from ‘electrons’ to ‘orbit around centre of an atom’ B1 line from ‘neutrons’ to ‘has no electric charge’ B1 12(b)(i) any 2 from: different forms of same element same number of protons different number of neutrons / nucleons B2 12(b)(ii) value from graph selected e.g. 16 000 C1 half the original value selected or stated e.g. 8000 C1 12.3 or 12.4 (years) A1

This question in 0625/32 Oct/Nov 2018

12 A nuclear power station uses uranium to generate thermal energy. (a) The fuel for the power station is an isotope of uranium. Explain the meaning of the term isotope. … … … [2] (b) When the nucleus of a uranium atom decays, it releases a β-particle. Describe the relative ionising effect, and the relative penetrating ability, of a β-particle. relative ionising effect … … relative penetrating ability … … [2] (c) A sample of rock includes some uranium-239. The half-life of uranium-239 is 23 minutes. Determine the fraction of the uranium-239 that remains after 46 minutes. fraction remaining = … [2] [Total: 6]

6 marks

Mark scheme: 12(a) (forms of the same element that have) same number of protons / proton number / atomic number B1 different number of neutrons / nucleon number B1 12(b) less (ionising) than alpha particle OR more (ionising) than gamma B1 more (penetrating) than alpha OR less (penetrating) than gamma B1 12(c) indication of two half-lives C1 ¼ OR 0.25 OR 25% A1

This question in 0625/33 Oct/Nov 2018

12 Astatine-210 is a radioactive material. The nucleus of astatine can be represented by the symbol shown. 21085At (a) Complete the table to describe the nucleus of astatine-210. type of particle number of particles charge on particle neutron positive [4] (b) Astatine-210 has a half-life of 8 hours. (i) The count rate of a sample of astatine-210 is measured over 24 hours. On Fig. 12.1, sketch a line to show how the count rate changes over the 24 hours. count rate 0 8 16 24 time / hours Fig. 12.1 [2] (ii) The mass of a sample of astatine-210 is 0.500 kg. Calculate how long it takes for 0.375 kg of the sample to decay. decay time = … hours [3] [Total: 9]

9 marks

Mark scheme: 12(a) (neutron) – 125 – neutral B2 proton(s) – 85 – (positive) B2 12(b)(i) curve of negative gradient, gradient decreasing B1 curve with negative gradient starts on y axis B1 12(b)(ii) 0.125 (kg) (remaining) C1 two half-lives indicated C1 16 hours A1

This question in 0625/32 Feb/March 2019

8 (a) A student rubs a plastic rod with a dry cloth, as shown in Fig. 8.1. The rod becomes negatively charged. plastic rod dry cloth Fig. 8.1 (i) Use words from the box to complete the sentence. air cloth electrons hand neutrons protons The rod becomes negatively charged because … move from the … to the rod. [2] (ii) The student moves the rod close to a suspended, charged rod. The two rods repel each other. State the type of charge on the suspended rod. … [1] (iii) Explain your answer to (a)(ii). … … [1] (b) A device has a metal case. Any charge on the case must be able to move to earth. (i) Draw one ring around a material that is suitable for the connection to earth. copper glass plastic rubber [1] (ii) Explain your answer to (b)(i). … … [1] [Total: 6]

6 marks

Mark scheme: 8(a)(i) electrons in 1st space B1 cloth in 2nd space B1 8(a)(ii) negative B1 8(a)(iii) like charges repel (each other) B1 8(b)(i) ring around copper B1 8(b)(ii) (earth wire must be good electrical ) conductor B1

This question in 0625/31 May/June 2019

12 (a) Use words from the box to complete the sentences about the charges in an atom. Words can be used once, more than once or not at all. negative neutral positive The charge on the nucleus of an atom is … The charge on a proton is … The charge on electrons orbiting the nucleus is … [3] (b) A nucleus of radium-226 has the nuclide notation shown. 226 88Ra (i) Determine the number of protons in a nucleus of radium-226. … [1] (ii) Determine the number of neutrons in a nucleus of radium-226. … [1] (iii) Radium has another isotope, radium-223. Write the nuclide notation for radium-223 in the space. [1] (c) Radium-226 has a half-life of 1600 years. A sample contains 8.0 mg of radium-226. Calculate the time for the sample to decay until only 1.0 mg of radium-226 remains. time = … years [2] [Total: 8]

8 marks

Mark scheme: 12(a) positive B1 positive B1 negative B1 12(b)(i) 88 B1 12(b)(ii) 138 B1 12(b)(iii) 223 88Ra B1 12(c) 3 half lives (until 1.0 mg remains) C1 (3 × 1600) = 4800 (years) A1

This question in 0625/31 May/June 2019

5 (a) A nuclear power station generates electrical energy. The main stages in the operation of the nuclear power station are listed. They are not in the correct order. E Electrical energy is produced. F The fission of uranium nuclei releases thermal energy. G A turbine drives a generator. H Thermal energy heats water to produce steam. Complete the flow chart to describe how a nuclear power station works. In each empty box, insert the letter for the correct statement. The nuclear power station uses uranium as a fuel. ↓ ↓ ↓ The steam drives a turbine. ↓ ↓ Electrical energy is transmitted. [2] (b) Electrical energy from the power station is used to power two different lamps. Fig. 5.1 shows how the light outputs from two types of lamp vary with the power input. 1000 power input filamentto lamp / W lamp 800 600 400 200 LED lamp 0 0 20 40 60 80 100 120 light output J/s Fig. 5.1 (i) An experiment requires a lamp with a light output of 70 J / s. For the LED lamp and for the filament lamp determine the input power required to give a light output of 70 J / s. Use information from Fig. 5.1. 1. For the LED lamp, input power = … W 2. For the filament lamp, input power = … W [2] (ii) Explain why using LED lamps is better for the environment. Use information from Fig. 5.1 in your answer. … … … … [2] [Total: 6]

6 marks

Mark scheme: 5(a) F then H B1 G then E B1 5(b)(i) 1 100 (W) B1 2 500 (W) B1 5 (b)(ii) less power OR energy used (by LED) B1 less CO2 OR greenhouse gases OR global warming B1

This question in 0625/32 May/June 2019

12 (a) Radioactive emission is a random process. Explain the meaning of the word random. … … [1] (b) The table compares three types of radioactive emission. emission relative ionising ability relative penetrating ability alpha beta gamma Table 12.1 Complete the table by choosing words from the box. high low medium [3] (c) A radioactive substance decays by emitting an α-particle. 4 An α-particle can be represented as α. 2 Draw a labelled diagram showing the composition of an α-particle. [3] [Total: 7]

7 marks

Mark scheme: 12(a)(i) unpredictable owtte B1 12(b) From top to bottom of table alpha: HIGH LOW B1 beta: MEDIUM MEDIUM B1 gamma: LOW HIGH B1 12(c) protons B1 neutrons B1 2 of each drawn/labelled AND no electrons B1

This question in 0625/32 May/June 2019

12 A radioactive substance decays by emitting an α-particle. (a) The nuclide notation for an α-particle is 4 2 α (i) State the term given to the number 4, written in the nuclide notation. … [1] (ii) State the term given to the number 2, written in the nuclide notation. … [1] (b) Fig. 12.1 shows the decay curve for a radioactive material. 1000 count rate counts / min 800 600 400 200 0 0 2 4 6 8 10 time / minutes Fig. 12.1 (i) Use information from the graph in Fig. 12.1 to determine the half-life of the material. Clearly show how you used the graph to obtain your answer. half-life = … minutes [3] (ii) Another radioactive material with the same half-life has an initial count rate of 600 counts / min. On Fig. 12.1 sketch the decay curve for this material. [1] [Total: 6]

6 marks

Mark scheme: 12(a)(i) nucleon number OR mass number B1 12(a)(ii) proton number OR atomic number B1 12(b)(i) selected count rate halved B1 two pairs of co-ordinates clearly indicated B1 (half-life =) 4 (minutes) B1 12(b)(ii) shallower curve drawn B1

This question in 0625/32 Oct/Nov 2019

12 Fig. 12.1 shows the nuclide notation for three isotopes of an element. 1 2 3 X Y Z 1 1 1 Fig. 12.1 (a) (i) Describe how the nuclide notation shows that each isotope is of the same element. … … [1] (ii) Describe how the nuclide notation shows the differences between the isotopes. … … [1] (b) Radioactive sources emit radiation when they decay. State the names of three types of radioactive emission. 1 … 2 … 3 … [2] (c) Radioactive emissions have differing characteristics. One characteristic is their ionising effect. Complete the statement about ionisation, using words from the box. The words can be used once, more than once or not at all. electrons negatively neutrons positively neutrally protons When atoms are ionised, … may be removed, leaving … charged atoms (ions), or … may be gained, forming … charged atoms (ions). [4] (d) Polonium-210 has a half-life of 140 days. A sample of polonium-210 has 8.0 × 1010 atoms. Calculate the number of polonium-210 atoms remaining in the sample after 280 days. number of atoms = … [2] [Total: 10]

10 marks

Mark scheme: 12(a)(i) same proton number OR same number of protons OR same atomic number OR same Z B1 12(a)(ii) different nucleon number OR different number of neutrons OR different mass number OR different A B1 12(b) alpha, beta and gamma OR symbols B2 12(c) top line: electrons – positive(ly) bottom line: electrons – negative(ly) B2 B2 12(d) two half-lives indicated 2.0 × 1010 (atoms remain) C1 A1

This question in 0625/33 Oct/Nov 2019

12 A nucleus of americium-241 has the nuclide notation shown. 24195Am (a) (i) Determine the number of neutrons in a nucleus of americium-241. number of neutrons = … [1] (ii) Determine the charge on a nucleus of americium-241. charge = … [2] (b) Americium-241 decays by emitting α-particles. Put a tick in the box next to each correct statement. α-particles are electromagnetic waves. α-particles are fast-moving electrons. α-particles are helium nuclei. α-particles are stopped by a sheet of paper. α-particles can pass through 3 cm of aluminium. [2] (c) Americium-241 has a half-life of 432 years. A sample contains 16 mg of americium-241. Calculate the time it takes until only 4.0 mg of americium-241 are left in the sample. time = … years [2] [Total: 7]

7 marks

Mark scheme: 12(a)(i) 146 B1 12(a)(ii) positive B1 95 B1 12(b) tick in 3rd box B1 tick in 4th box B1 12(c) idea of 2 half-lives C1 (432 × 2) = 864 (years) A1

This question in 0625/32 Feb/March 2020

12 Radioactive sources emit α-(alpha), β-(beta) and γ-(gamma) radiations. (a) State which of these types of radiation can pass through paper. … [1] (b) Barium-137 is a radioactive isotope. The nuclide notation for barium-137 is 13756Ba Determine the number of neutrons in a nucleus of barium-137. number of neutrons = … [1] (c) An isotope of barium-137 has a half-life of 3 minutes. A radioactive source contains 36 mg of this isotope. Calculate the mass of the isotope that remains in the source after 9 minutes. mass of the isotope remaining = … mg [3] [Total: 5]

5 marks

Mark scheme: 12(a) beta / β AND gamma / γ B1 12(b) (137 – 56 =) 81 B1 12(c) idea of three half-lives C1 36 ÷ 8 C1 4.5 (mg) A1

This question in 0625/31 May/June 2020

12 (a) Carbon-14 is a radioactive isotope of carbon. An atom of carbon-14 has 6 protons in its nucleus. Another isotope of carbon is carbon-12. (i) Determine the number of protons in a carbon-12 nucleus. … [1] (ii) Determine the number of neutrons in a carbon-14 nucleus. … [1] (iii) Determine the number of electrons orbiting the nucleus of a single carbon-14 atom. … [1] (b) Carbon-14 decays by emitting a β-particle. State what happens to a nucleus of carbon-14 when it emits a β-particle. … [1] (c) People working with radioactive sources need to take safety precautions. (i) A shielding material can absorb ionising radiation and reduce the damage to living tissue. State a suitable material that will absorb all types of naturally occurring nuclear radiation. … [1] (ii) Apart from using shielding, state how a person can reduce the amount of ionising radiation they absorb when they handle samples of radioactive substances. … [1] [Total: 6]

6 marks

Mark scheme: 12(a)(i) 6 B1 12(a)(ii) 8 B1 12(a)(iii) 6 B1 12(b) changes to a different element / gains a proton B1 12(c)(i) lead B1 12(c)(ii) any one from: minimise time for handling maximise distance from source use of shielding prevent contamination B1

This question in 0625/32 May/June 2020

11 (a) Fig. 11.1 represents the particles in a neutral lithium atom. orbits Fig. 11.1 Use the information in Fig. 11.1 about the lithium atom to answer (a)(i), (a)(ii) and (a)(iii). (i) Determine the number of electrons. … [1] (ii) Determine the value of the nucleon number. … [1] (iii) Determine the number of neutrons. … [1] (b) The count rate of a radioactive sample is 2400 counts per minute at 10 am on one day. The half-life of the sample is two days. Predict the count rate at 10 am four days later. count rate = … counts per minute [3] [Total: 6]

6 marks

Mark scheme: 11(a)(i) 3 (electrons) B1 11(a)(ii) 7 (is the nucleon number) B1 11(a)(iii) 4 (neutrons) B1 Question Answer Marks 11(b) (four days is) 2 half-lives C1 activity is 2400 ÷ 4 C1 600 (counts / minute) A1

This question in 0625/31 Oct/Nov 2020

11 (a) Fig. 11.1 represents the structure of four atoms P, Q, R and S. Key + proton + electron + + + + + + + neutron P Q R S Fig. 11.1 State which two atoms are isotopes of the same element and explain your answer. … and … explanation … … [2] (b) Radiographers use X-ray machines in hospitals. X-rays can cause damage to living things. (i) State an example of the damage that may be caused by X-rays. … [1] (ii) State and explain how radiographers can be protected from damage caused by X-rays. … … … [2] (c) A radioactive source is placed near to a detector, as shown in Fig. 11.2. The meter shows a reading of 239 counts per second. meter detector radioactive source 239 Fig. 11.2 A sheet of paper is placed between the detector and the radioactive source. The meter shows a reading of 240 counts per second. The sheet of paper is removed and a thin sheet of aluminium is placed between the detector and the radioactive source. The meter shows a reading of 3 counts per second. (i) Deduce the type of radiation emitted by the radioactive source. … [1] (ii) The radioactive source is removed. The meter shows a reading of 3 counts per second. State why the meter does not show a reading of zero counts per second. … [1] [Total: 7]

7 marks

Mark scheme: 11(a) P AND R B1 same number of protons B1 11(b)(i) alters genes / DNA OR kills cells OR (cell) mutations OR cancer B1 11(b)(ii) stand behind a screen / wear a lead apron B1 screen / apron absorbs X-rays OR X-rays cannot penetrate screen / apron B1 11(c)(i) beta / β B1 11(c)(ii) background (radiation) B1

This question in 0625/33 Oct/Nov 2020

11 Carbon-12 is a stable isotope of carbon. Its nuclide notation is shown in Fig. 11.1. Carbon-14 is an unstable isotope of carbon. Its nuclide notation is shown in Fig. 11.2. 12C 14C 6 6 Fig. 11.1 Fig. 11.2 (a) Determine the numbers of electrons, protons and neutrons in an atom of carbon-12 and the numbers of electrons, protons and neutrons in an atom of carbon-14. Complete Table 11.1. Table 11.1 carbon-12 carbon-14 number of electrons number of protons number of neutrons [3] (b) Fig. 11.3 shows the decay curve for a sample of carbon-14. 18 000 count rate 16 000 counts / s 14 000 12 000 10 000 8 000 6 000 4 000 2 000 0 0 5000 10 000 15 000 20 000 25 000 time / years Fig. 11.3 Use the graph to determine the half-life of carbon-14. half-life = … years [2] [Total: 5]

5 marks

Mark scheme: 11(a) carbon-12 carbon-14 number of electrons 6 6 B1 number of protons 6 6 B1 number of neutrons 6 8 B1 3 11(b) any indication on graph of line from 8000 C1 5600 (years) A1

This question in 0625/32 Feb/March 2021

12 (a) Table 12.1 describes four nuclides. Table 12.1 name of nuclide plutonium-238 thorium-234 uranium-235 uranium-238 238 234 235 238 nuclide notation Pu Th U U 94 90 92 92 (i) State which two nuclides have the same number of protons. … [1] (ii) State which two nuclides have the same number of nucleons. … [1] (iii) State which one of the four nuclides has the most electrons orbiting when it is in a neutral atom. … [1] (b) Thorium-234 has a half-life of 24 days. A sample of radioactive material contains 40 mg of thorium-234. Calculate the mass of thorium-234 remaining after 72 days. mass of thorium-234 remaining = … mg [3] [Total: 6]

6 marks

Mark scheme: 12(a)(i) uranium-235 AND uranium-238 B1 12(a)(ii) plutonium(-238) AND uranium-238 B1 12(a)(iii) plutonium(-238) B1 12(b) idea of 3 half-lives OR 72 ÷ 24 B1 40 ÷ 8 C1 5(.0) (mg) A1

This question in 0625/31 May/June 2021

11 (a) The nuclide notation describes the nucleus of an atom. ZX Draw a line from each symbol to the correct description of the symbol. symbol description half-life value A neutron number nucleon number Z type of radiation proton number [2] (b) The activity of a sample of a radioactive nuclide is measured in June of each year. In June 2004 the activity was 80 000 counts / s. In June 2014 the activity was 20 000 counts / s. (i) Show that the half-life of the nuclide is 5 years. [3] (ii) Determine the year when the activity of the sample was 10 000 counts / s. year = … [2] [Total: 7]

7 marks

Mark scheme: 11(a) line from Z to bottom box: proton number B1 11(b)(i) (from June 2004 to June 2014 =) 10 (years) B1 (decrease in activity from) 80 000 (Bq) to 20 000 (Bq) takes 2 half-lives B1 10 ÷ 2 = (5 years) B1 11(b)(ii) (decrease in activity from) 20 000 (Bq) to 10 000 (Bq) is one half-life C1 so half the time difference = 5 years OR 2019 A1

This question in 0625/32 May/June 2021

12 (a) State which radioactive emission is: (i) the most penetrating … [1] (ii) the most ionising. … [1] (b) Explain the meaning of the term isotope. … … [2] (c) The isotope iodine-131 is used in hospitals. A sample of iodine-131 is prepared for use. The half-life of iodine-131 is 8 days. Determine the fraction of iodine-131 remaining in the sample after 16 days. fraction remaining = … [2] [Total: 6]

6 marks

Mark scheme: 12(a)(i) gamma OR B1 12(a)(ii) alpha OR B1 12(b) same atomic number / Z / number of protons B1 different nucleon number / A / number of neutrons B1 12(c) idea of 2 half-lives C1 1 / 4 A1

This question in 0625/32 Oct/Nov 2021

12 (a) Table 12.1 gives some properties of three different types of radiation. Table 12.1 type of radiation nature relative charge ionising ability electromagnetic gamma (γ) 0 low wave beta (β) –1 (minus one) medium alpha (α) helium nucleus (i) Complete Table 12.1 by writing the missing property in each of the empty boxes. [3] (ii) State which type of radiation, alpha, beta or gamma, is the most penetrating. … [1] (b) An isotope of beryllium, Be, has the nuclide notation: 94Be. Fig. 12.1 shows a diagram of one atom of this isotope. electron X Y Fig. 12.1 (not to scale) Complete the labelling of Fig. 12.1. State the names for X and for Y. X … Y … [2] [Total: 6]

6 marks

Mark scheme: 12(a)(i) (1st column:) electron B1 (2nd column:) plus two OR +2 B1 (3rd column:) high B1 12(a)(ii) gamma OR γ B1 12(b) (X is a ) proton(s) B1 (Y is a ) neutron(s) B1

This question in 0625/32 Feb/March 2022

11 (a) An isotope of americium has 95 protons and 146 neutrons in its nucleus. Write the nuclide notation for the nucleus of this isotope. The chemical symbol for americium is Am. [2] (b) Fig. 11.1 shows how the count rate of a sample of americium changes with time. 18 000 16 000 count rate counts / min 14 000 12 000 10 000 8000 6000 4000 2000 0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 time / years Fig. 11.1 Determine the half-life of the americium in the sample. Use information from Fig. 11.1. half-life = … years [2] [Total: 4]

4 marks

Mark scheme: 11(a) 241 95(Am) B1 11(b) 430 (years) A2 (decrease in activity from ) 16 000 (counts/min) to 8000 (counts/min) (C1)

This question in 0625/32 May/June 2022

10 (a) State the names of three types of radioactive emission. 1. … 2. … 3. … [3] (b) In nuclide notation, 3517Cl represents one nuclide of chlorine. For one neutral atom of 3517Cl, state: (i) the nucleon number … [1] (ii) the proton number … [1] (iii) the number of neutrons. … [1] (c) Complete the sentence: In a neutral atom, the number of protons is equal to the number of … . [1] [Total: 7]

7 marks

Mark scheme: 10(a) B1 beta/ B1 gamma/ B1 10(b)(i) 35 B1 10(b)(ii) 17 B1 10(b)(iii) 18 B1 10(c) electrons B1

This question in 0625/33 May/June 2022

10 (a) α (alpha)-particles, β (beta)-particles and γ (gamma)-rays have different characteristics. Complete Table 10.1 by indicating with a tick (3) the correct type of radiation for each characteristic. The first row is done for you. Table 10.1 characteristic type of radiation α (alpha)-particles β (beta)-particles γ (gamma)-rays electromagnetic wave 3 least ionising least penetrating a helium nucleus negatively charged [3] (b) The nucleus of an isotope of plutonium has 94 protons and 147 neutrons. The chemical symbol for plutonium is Pu. Write the nuclide notation that describes this nucleus. [2] (c) A sample contains 8.0 × 1012 atoms of a radioactive isotope of plutonium. The half-life of this isotope of plutonium is 14 years. Calculate the number of atoms of this isotope of plutonium remaining in the sample after 28 years. number of atoms of plutonium remaining = … [3] [Total: 8]

8 marks

Mark scheme: 10(a) 4 correct ticks for 3 marks B3 2 or 3 correct ticks for 2 marks 1 correct tick for 1 mark characteristic type of radiation  (alpha)-particles  (beta)-particles  (gamma)-rays electromagnetic wave (✓) least ionising ✓ least penetrating ✓ a helium nucleus ✓ negatively charged ✓ 10(b) 241 B1 (Pu) 94 B1 10(c) 2(.0)  1012 (atoms) A3 1 1 C2 8(.0) ( 1012) / 4 OR 8(.0) ( 1012)   2 2 28 years = 2 half-lives OR 28 years / 14 = 2 (half-lives) C1

This question in 0625/31 Oct/Nov 2022

11 Fig. 11.1 represents an atom of carbon-14. proton X Y Fig. 11.1 (a) (i) State the name of the particle labelled X. … [1] (ii) State the name of the particle labelled Y. … [1] (iii) State the nucleon number of carbon-14. … [1] (b) Carbon-14 decays by emitting a β (beta)-particle. State the nature of a β (beta)-particle. … [1] (c) Scientists find an ancient wooden spoon. They find that the spoon contains 2000 atoms of carbon-14. When the spoon was made, it contained 16 000 atoms of carbon-14. The half-life of carbon-14 is 5800 years. Calculate the age of the ancient spoon. age of spoon = … years [2] [Total: 6]

6 marks

Mark scheme: 11(a)(i) neutron B1 11(a)(ii) electron B1 11(a)(iii) 14 B1 11(b) electron B1 11(c) 17 400 A2 16000 – 8000 – 4000 – 2000 OR 3 half lives (C1)

This question in 0625/32 Oct/Nov 2022

10 (a) State which radioactive emission: (i) is the most penetrating … [1] (ii) is the most ionising … [1] (iii) has a positive charge. … [1] (b) Iodine-131 is a radioactive isotope that is commonly used in medicine. The nuclide notation for a nucleus of iodine-131 is: 131 53I (i) Determine the number of protons in one nucleus of iodine-131. … [1] (ii) Determine the number of neutrons in one nucleus of iodine-131. … [1] (c) Radioactive iodine-131 has a half-life of 8 days. The activity of a sample of iodine-131 is 1600 counts / s. Calculate the activity of this sample after 24 days. activity = … counts / s [2] [Total: 7]

7 marks

Mark scheme: 10(a)(i) gamma /  B1 10(a)(ii) alpha /  B1 10(a)(iii) alpha /  B1 10(b)(i) 53 B1 10(b)(ii) 78 B1 10(c) 200 (counts / s) A2 1600 – 800 – 400 – 200 OR idea of 3 half lives (C1)

This question in 0625/33 Oct/Nov 2022

11 Americium-241 is a radioactive nuclide. The nuclide notation for a nucleus of americium-241 is 241 Am 95 (a) Determine the number of: protons in one nucleus of americium-241, … [1] neutrons in one nucleus of americium-241. … [1] (b) Americium-241 has a half-life of 430 years. A radioactive source contains 12 mg of americium-241. Calculate the mass of americium-241 that remains in the source after 860 years. mass of americium-241 remaining = … mg [3] [Total: 5]

5 marks

Mark scheme: 11(a) 95 B1 146 B1 11(b) (amount remaining =) 3(.0) (mg) A3 (amount remaining =) 12  ½  ½ OR 12  1/4 (C2) 860 years is 2 half-lives (C1)

This question in 0625/32 Feb/March 2023

11 Fig. 11.1 represents all the particles in an atom which is a radioactive isotope of carbon. nucleus Fig. 11.1 (not to scale) (a) Table 11.1 gives information about the particles shown in Fig. 11.1. Using the information in Fig. 11.1, write in the empty boxes to complete Table 11.1. Table 11.1 name of number of position of relative charge of particle particles particle particle electron neutron in the nucleus 6 +1 (plus one) [4] (b) A museum displays an item made of ancient wood. When the wood was new, the item contained 8.00 mg of the isotope shown in Fig. 11.1. The item now contains 2.00 mg of the isotope. The half-life of the isotope is 5700 years. Calculate the age of the wood in the item. age of wood = … years [3] [Total: 7]

7 marks

Mark scheme: 11(a) name of particle number of particles position of particle relative charge of particle electron 6 orbiting / outside (nucleus) –1 OR minus one neutron 8 in the nucleus 0 OR zero OR none OR neutral proton 6 (in the) nucleus +1 (plus one) 1 mark for each correct column 11(b) (2  5700 =) 11 400 (years) A3 (change in mass takes place over / decay takes) 2 half-lives (C2) 8(.00) → 4(.00) → 2.(00) OR 8(.00)  ½  ½ = 2.(00) (C1)

This question in 0625/31 May/June 2023

10 Iodine-131 is a radioactive isotope of the element iodine. Fig. 10.1 shows the nuclide notation for a nucleus of iodine-131. 131 I 53 Fig. 10.1 (a) (i) Determine the number of protons in one nucleus of iodine-131. number of protons = … [1] (ii) Determine the number of neutrons in one nucleus of iodine-131. number of neutrons = … [1] (b) When a nucleus of iodine-131 decays, it emits a beta (β)-particle and a gamma (γ) ray. State the nature of a beta-particle and a gamma ray. A beta-particle is … A gamma ray is … [2] (c) A sample contains 1.6 mg of iodine-131. The half-life of iodine-131 is 8.0 days. Calculate the mass of iodine-131 remaining in the sample after 24.0 days. mass of iodine-131 remaining = … mg [3] [Total: 7]

7 marks

Mark scheme: 10(a)(i) 53 B1 10(a)(ii) (131 – 53 =) 78 B1 10(b) (negatively charged) electron B1 electromagnetic (wave / ray) B1 10(c) 0.2(0) (mg) A3 1.6  ½  ½  ½ OR 1.6 ÷ 8 OR 1.6, 0.8, 0.4 (C2) 24(.0) ÷ 8(.0) OR idea of 3 half-lives (C1)

This question in 0625/32 May/June 2023

9 Fig. 9.1 represents an atom of beryllium. The labels A, B and C indicate three types of particle. A B C Fig. 9.1 (a) (i) Complete Table 9.1. Name each type of particle and state the sign of its charge. One row is done for you. Table 9.1 type of particle name sign of charge A B C proton positive (+) [3] (ii) There are several different isotopes of beryllium. State what is meant by the term isotope. … … [2] (b) Fig. 9.2 shows sources of background radiation that affect people. rocks and buildings region radon gas D (in the air) food and drink Fig. 9.2 Suggest the source of background radiation in region D. … [1] (c) The nuclide notation for an atom of radon is: 22286Rn (i) State the number of protons in this atom of radon. … [1] (ii) State the number of particles in the nucleus of this atom of radon. … [1] [Total: 8]

8 marks

Mark scheme: 9(a)(i) type of particle name sign of charge A electron negative / – B neutron neutral / no charge / zero / 0 C proton positive (+) 4 correct – 3 marks 3 or 2 correct – 2 marks 1 correct – 1 mark B3 9(a)(ii) same number of protons / proton number / atomic number / Z B1 different number of neutrons / nucleon number / mass (number) / A B1 9(b) cosmic (radiation) B1 9(c)(i) 86 B1 9(c)(ii) 222 B1

This question in 0625/33 May/June 2023

10 A nucleus of an isotope of actinium contains 89 protons and 136 neutrons. The chemical symbol for actinium is Ac. (a) (i) Complete the nuclide notation for this isotope of actinium. … … Ac [1] (ii) State the number of electrons orbiting the nucleus of a neutral atom of this isotope. number of electrons = … [1] (b) A sample contains 8.0 mg of this isotope of actinium. The isotope of actinium has a half-life of 10.0 days. The graph in Fig. 10.1 shows the original mass of the actinium in the sample and its mass after 10 days. On Fig. 10.1, plot two more points for the mass remaining after 20 days and 30 days. Draw the decay curve for the sample over 30 days. 10 8 6 mass of isotope remaining / mg 4 2 0 0 5 10 15 20 25 30 time / days Fig. 10.1 [3] [Total: 5]

5 marks

Mark scheme: 10(a)(i) (nucleon number =) 225 B1 (Ac) (proton number =) 89 10(a)(ii) (number of electrons =) 89 B1 10(b) point at (20, 2.0) plotted correctly B1 point at (30, 1.0) plotted correctly B1 points joined by a (smooth) curve to about 30 days B1

This question in 0625/31 Oct/Nov 2023

11 Fig. 11.1 represents all the particles in a beryllium atom. Key electrons protons … Fig. 11.1 (not to scale) (a) (i) The symbol for the element beryllium is Be. Give the nuclide notation for the isotope shown in Fig. 11.1. … … Be [1] (ii) The key for Fig. 11.1 gives the names of two types of particle. One label is missing. Complete the key by adding the name of the third type of particle shown in Fig. 11.1. [1] (b) Fig. 11.2 shows four different particle diagrams, A, B, C and D. A B C D Fig. 11.2 (i) State which diagrams show an isotope of beryllium. … [1] (ii) State which diagram shows a positive ion. … [1] (c) A scientist uses a detector and counter to measure the count rate due to radiation emitted from a radioactive source. The first measurement is 400 counts / min. The scientist takes another measurement 6 hours later. This measurement is 50 counts / min. Calculate the half‑life of the radioactive source. half‑life = … h [2] [Total: 6]

6 marks

Mark scheme: 11(a)(i) 94Be B1 11(a)(ii) neutron(s) B1 11(b)(i) A and B and D B1 11(b)(ii) A B1 11(c) 2 (h) A2 3 half lives (C1)

This question in 0625/32 Oct/Nov 2023

10 (a) Fig. 10.1 represents all the particles in a lithium atom. Key electron proton neutron Fig. 10.1 (not to scale) (i) State the proton number (atomic number) of the lithium atom in Fig. 10.1. … [1] (ii) Determine the nucleon number (mass number) of the lithium atom in Fig. 10.1. nucleon number = … [1] (iii) Describe how a lithium atom changes to form a positive ion. … [1] (b) The half-life of iodine-131 is 8 days. A sample contains 80 mg of iodine-131. Calculate the time taken to decay until 10 mg of iodine-131 remain in the sample. time taken = … days [2] [Total: 5]

5 marks

Mark scheme: 10(a)(i) 3 B1 10(a)(ii) 7 B1 10(a)(iii) lose electron(s) B1 10(b) 24 (days) A2 3 half lives (C1)

This question in 0625/33 Oct/Nov 2023

10 (a) Fig. 10.1 represents an atom of carbon. neutron … … Fig. 10.1 (not to scale) Complete the labels for the particles in Fig. 10.1. On each dotted line, write the name of the particle. [2] (b) An atom of lithium has the nuclide notation: 7 3 Li Draw a clearly labelled diagram to represent one atom of lithium. [3] (c) An isotope of carbon has a half-life of 5700 years. A sample contains 120 mg of this isotope. Calculate the time taken for this isotope of carbon to decay from 120 mg to 15 mg. time taken = … years [2] [Total: 7]

7 marks

Mark scheme: 10(a) electron B1 proton B1 10(b) any three from: B3 3 protons (in nucleus) 4 neutrons (in nucleus) 3 electrons outside nucleus nucleus labelled electron orbits seen 10(c) (5700  3 =) 17 100 (years) A2 (from 120 mg to 15 mg takes) 3 half-lives (C1)

This question in 0625/32 Feb/March 2024

10 A nucleus of strontium-90 is represented using nuclide notation as shown. 90 38 Sr (a) (i) Calculate the number of neutrons in one nucleus of strontium-90. number of neutrons = … [2] (ii) Determine the number of electrons in one atom of strontium-90. number of electrons = … [1] (b) Strontium-90 decays by emitting β-particles (beta-particles). Describe the nature of β-particles. … [1] (c) Strontium-90 decays with a half-life of 29 years. A sample contains 16 mg of strontium-90. Calculate the time taken for the strontium-90 to decay until only 2.0 mg of strontium-90 remains in the sample. time = … years [2] [Total: 6]

6 marks

Mark scheme: 10(a)(i) (number of neutrons =) 52 A2 nucleon number – proton number = number of neutrons OR 90 – 38 (C1) 10(a)(ii) 38 B1 10(b) (beta-particles are fast-moving / negatively charged) electrons B1 10(c) (29  3 =) 87 years A2 idea of 3 half-lives OR 16 ÷ 23 (= 2) (C1)

This question in 0625/31 May/June 2024

10 (a) U-235 and U-238 are isotopes of uranium. Fig. 10.1 shows the nuclide notation for U-235 and for U-238. 235 238 92U 92U Fig. 10.1 (i) Compare the number of protons in one nucleus of U-235 with the number of protons in one nucleus of U-238. … … [1] (ii) Compare the number of neutrons in one nucleus of U-235 with the number of neutrons in one nucleus of U-238. … … [1] (b) A sample contains another isotope of uranium. The half-life of this isotope is 24 minutes. Calculate the time taken for the mass of this isotope in the sample to decay from 16.0 mg to 4.0 mg. time taken = … minutes [3] [Total: 5]

5 marks

Mark scheme: 10(a)(i) both have 92 (protons) OR same (number of protons) B1 10(a)(ii) U-235 has (3) fewer neutrons OR U-238 has (3) more neutrons OR U-235 has 143 and U-238 has 146 neutrons B1 10(b) (2  24 =) 48 (minutes) A3 (change in mass takes place over / decay takes) 2 half-lives (C2) 16  8(.0)  4(.0) OR 16  ½  ½ (= 4(.0)) (C1)

This question in 0625/32 May/June 2024

10 (a) The nuclide notation for an atom of protactinium‑234 is: 23491Pa (i) State the number of protons in an atom of protactinium‑234. … [1] (ii) State the number of nucleons in an atom of protactinium‑234. … [1] (b) Three forms of the element protactinium are: protactinium‑234, protactinium‑230 and protactinium‑233. State the name given to these different forms of the same element. … [1] (c) A teacher demonstrates radioactive decay by using a sample of protactinium‑234m. (i) The sample emits beta (β)‑particles. State the nature of a beta (β)‑particle. … [1] (ii) The teacher obtains data for a decay curve. Fig. 10.1 shows the decay curve for the sample of protactinium‑234m. 1000 900 count rate count / s 800 700 600 500 400 300 200 100 0 0 50 100 150 200 250 300 350 time / s Fig. 10.1 Calculate the half‑life of protactinium‑234m using the information in Fig. 10.1. Clearly show your working on the graph or in the space provided. half‑life = … s [3] (iii) Suggest a reason why the half‑life of protactinium‑234m makes it suitable for this demonstration in a lesson. … … [1] [Total: 8]

8 marks

Mark scheme: 10(a)(i) 91 B1 10(a)(ii) 234 B1 10(b) isotopes B1 10(c)(i) electron B1 10(c)(ii) range 65–75 (s) A3 range 55–85 (s) (C2) 2 associated values (e.g. 900 and 450 or 800 and 400 etc) seen / indicated (C1) small half-life / time in a lesson to collect enough data for a decay curve owtte B1

This question in 0625/33 May/June 2024

10 (a) (i) State how a neutral atom becomes a positive ion. … [1] (ii) State the type of nuclear emission which is the most ionising. … [1] (b) Isotopes of copper (Cu) include: Cu - 63 and Cu - 65. Explain what is meant by ‘isotopes of copper’. … … [2] (c) A teacher provides the data in Table 10.1 about the decay of a radioactive sample. Table 10.1 count rate time / s counts / s 0 300 22 200 44 150 66 100 88 75 Use the information in Table 10.1 to determine the half-life of the radioactive sample. half-life = … s [2] (d) Describe how to store radioactive materials safely. … … [1] [Total: 7]

7 marks

Mark scheme: 10(a)(i) lose an electron / negative charge B1 10(a)(ii) alpha /  (particle) B1 10(b) same number of protons B1 different number of neutrons B1 10(c) 44 (s) A2 pair of time values for count rates of 300 and 150 or 200 and 100 or 150 and 75 (C1) 10(d) lead container OR lead safe B1

This question in 0625/33 Oct/Nov 2024

11 (a) Table 11.1 gives information about the particles in an atom. Table 11.1 name of particle relative charge location in the atom proton +1 in the nucleus neutron electron orbiting the nucleus Complete the table by writing the correct information in the three empty spaces. [3] (b) State the relative charge on an alpha particle. … [1] (c) Compare the penetrating abilities of alpha particles, beta particles and gamma rays. … … … … [2] [Total: 6]

6 marks

Mark scheme: 11(a) B3 name of particle relative charge location in the atom proton +1 in the nucleus neutron 0 OR zero in the nucleus electron –1 OR minus 1 orbiting the nucleus B1 B1 B1 11(b) +2 OR plus two B1 11(c) any two from: B2 gamma (rays) most / more penetrating alpha (particles) least / less penetrating beta are between alpha and gamma

This question in 0625/32 Feb/March 2025

10 (a) Table 10.1 describes four nuclides. Table 10.1 americium-241 plutonium-239 plutonium-241 uranium-238 nuclide 241 239 241 238 Am Pu Pu U notation 95 94 94 92 (i) Determine which two nuclides have the same number of nucleons. … [1] (ii) Determine which nuclide has the largest number of neutrons. … [2] (b) Plutonium-241 has a half-life of 14 years. A sample of radioactive material contains 72 mg of plutonium-241. Calculate the mass of plutonium-241 remaining in the sample after 42 years. mass of plutonium-241 remaining = … mg [3] [Total: 6]

6 marks

Mark scheme: 10(a)(i) plutonium-241 AND americium(-241) B1 10(a)(ii) plutonium-241 OR 24194Pu OR Pu-241 A2 (Am =) 241 − 95 OR 146 OR (Pu-239 =) 239 − 94 OR 145 C1 OR (Pu-241 =) 241 − 94 OR 147 OR (U =) 238 − 92 OR 146 10(b) 9(.0) (mg) A3 72  ½  ½  ½ OR 72  {1÷8} C2 idea that 42 years = 3 half-lives C1

This question in 0625/31 May/June 2025

10 (a) Radon-222 is a radioactive gas that emits alpha (α) particles. 222 The nuclide notation for radon-222 is 86Rn. (i) State the number of protons in one nucleus of radon-222. number of protons = … [1] (ii) Determine the number of neutrons in one nucleus of radon-222. number of neutrons = … [1] (b) A sample containing 60 mg of radon-222 decays to 7.5 mg in 11.5 days. Calculate the half-life of radon-222. half-life = … days [3] (c) Radon gas is one source of background radiation. Name two other sources that make a significant contribution to background radiation. 1 … 2 … [2] [Total: 7]

7 marks

Mark scheme: 10(a)(i) 86 B1 10(a)(ii) 136 B1 10(b) 3.8 (days) A3 11.5 ÷ 3 C2 3 half-lives C1 10(c) any two from: B2 • rocks • buildings • food • drink • cosmic (rays)

This question in 0625/32 May/June 2025

10 (a) Radon-222 is a radioactive gas that emits alpha (α) particles. 222 The nuclide notation for radon-222 is 86Rn. (i) State the number of protons in one nucleus of radon-222. number of protons = … [1] (ii) Determine the number of neutrons in one nucleus of radon-222. number of neutrons = … [1] (b) A sample containing 60 mg of radon-222 decays to 7.5 mg in 11.5 days. Calculate the half-life of radon-222. half-life = … days [3] (c) Radon gas is one source of background radiation. Name two other sources that make a significant contribution to background radiation. 1 … 2 … [2] [Total: 7]

7 marks

Mark scheme: 10(a)(i) 86 B1 10(a)(ii) 136 B1 10(b) 3.8 (days) A3 11.5 ÷ 3 C2 3 half-lives C1 10(c) any two from: B2 • rocks • buildings • food • drink • cosmic (rays)

This question in 0625/33 May/June 2025

10 Radium is a radioactive element with the chemical symbol Ra. The proton number for radium is 88. Radium-223 is an isotope of radium that has a nucleon number of 223. (a) Write the nuclide notation for radium-223. [2] (b) Determine the number of neutrons in one nucleus of radium-223. number of neutrons = … [1] (c) The half-life of radium-223 is 11 days. A sample contains 32 mg of radium-223. Calculate the time taken for the mass of radium-223 in the sample to decay from 32 mg to 4 mg. number of days = … [3] [Total: 6]

6 marks

Mark scheme: 10(a) 223 B1 Ra 88 B1 10(b) (number of neutrons = 223 – 88 = ) 135 B1 10(c) (3  11 =) 33 (days) A3 (change in mass takes place over / decay takes) 3 half-lives (C2) 32 16 8(.0) 4(.0) OR 32  ½  ½  ½ OR 32  1/8 (C1)

This question in 0625/31 Oct/Nov 2025

9 Unstable nuclei emit ionising radiation when they decay. (a) Draw one line from each type of ionising radiation to its nature. type of ionising radiation nature electromagnetic alpha (α) wave beta (β) helium nucleus gamma (γ) electron [2] (b) Iodine-131 is an unstable isotope of iodine. (i) State the meaning of the term isotope. … … [2] (ii) Fig. 9.1 shows the decay curve for a sample of iodine-131. 240 count rate 210 counts / s 180 150 120 90 60 30 0 0 4 8 12 16 20 24 28 32 36 40 time / days Fig. 9.1 Determine the half-life of iodine-131. Show your working clearly. half-life = … days [3] [Total: 7]

7 marks

Mark scheme: 9(a) B2 9(b)(i) (atoms with) same number of protons / proton number / atomic number / Z B1 different number of neutrons / nucleon number / mass number / A B1 9(b)(ii) 8 (days) A3 matching pair of x coordinates C2 suitable pair of y coordinates C1

This question in 0625/32 Oct/Nov 2025

9 (a) Table 9.1 shows information about particles in an atom. Complete the table. Table 9.1 particle charge on particle location of particle positive neutron in the nucleus negative [3] (b) Fig. 9.1 represents three types of emission P, Q and R from a radioactive nucleus. The diagram shows whether each emission can penetrate paper and aluminium. P Q R thin sheet 5 mm of of paper aluminium Fig. 9.1 Identify the types of emission labelled P, Q and R. Type P is … Type Q is … Type R is … [3] (c) State two precautions for storing radioactive materials safely. 1 … 2 … [2] [Total: 8]

8 marks

Mark scheme: 9(a) B1 proton B1 inside the nucleus neutral / zero / 0 B1 electron outside the nucleus 9(b) P –  / beta (particle) B1 Q –  / alpha (particle) B1 R –  / gamma (ray) B1 9(c) any two from: B2 • use a lead (lined) box / container or concrete room • idea of remote / area location / away from main building • locked room / secure area • radiation sign on door / in place • only remove / use for short time owtte

This question in 0625/33 Oct/Nov 2025