Nuclear equations

The photograph shows a cloud chamber, used to observe alpha radiation produced by a radioactive source. The radioactive source is inside the cloud chamber, as shown in the photograph.

Describe the structure of an alpha particle.

The source used in the cloud chamber contains the isotope radium-226.

The incomplete nuclear equation shows the decay of radium-226 into an isotope of radon.

Complete the nuclear equation by writing the correct numbers in the boxes.

The tracks in the cloud chamber can be seen through the glass viewing window.

Explain why the radioactive source is not a hazard to the person viewing the cloud chamber.

When radiation is emitted from the source a white line is produced in the cloud chamber. The white line is known as a track.

The diagram shows the tracks produced by the radiation from the source.

The diameter of the cloud chamber is also shown.

Explain the properties of alpha radiation that can be deduced from the length of the tracks.

Uranium‑239 is an isotope of the element uranium.

State what is meant by the term isotopes.

Uranium‑239 can be represented using the symbol

Protons are one type of particle found in the nucleus of an atom.

How many protons are in the nucleus of an atom of uranium‑239?

Give the name of the other particle found in the nucleus of an atom of uranium‑239.

Uranium‑239 is radioactive and decays by beta emission.

Uranium‑239 has a half‑life of 23 minutes.

A sample of uranium‑239 has an initial mass of 60 g.

Calculate the mass of uranium‑239 remaining after 46 minutes.

When uranium‑239 undergoes beta decay, an isotope of the element neptunium, Np, is produced.

Which of these is the correct symbol for the neptunium nucleus produced in the beta decay of uranium‑239?

This question is about nuclear decay.

Which of these is the same as a beta particle?

Which of these is the same as an alpha particle?

Complete the nuclear equation for an alpha decay.

This question is about radioactivity.

The nucleus of an atom of carbon has 6 protons and 8 neutrons.

Which row of the table shows the nucleus of an atom that is a different isotope of carbon?

Which type of radiation is a high-energy electron?

A nucleus emits radiation. This causes the mass number to decrease by one. The atomic number stays the same.

Which type of radiation does the nucleus emit?

The nucleus of an isotope of uranium can be represented using this symbol.

The nucleus forms part of a positively charged ion.

How many electrons could be in this ion?

A radioactive isotope has an initial activity of 400 Bq.

The half-life of the isotope is 8 hours.

What is the activity of the isotope after 16 hours?

This question is about using carbon dating to find the age of pieces of wood.

The equation shows how carbon-14 forms in the atmosphere.

State the name of particle X.

Carbon-14 decays by beta decay.

State what happens to the number of protons and the number of neutrons in a carbon-14 nucleus when it decays.

A scientist determines how the percentage of carbon-14 remaining in a sample of wood changes with time.

The table shows the scientist’s data.

Plot the scientist’s data on the grid.

Draw the curve of best fit.

Use the graph to determine the age of a sample of wood that has 36% of its carbon-14 remaining.

Carbon-14 dating is inaccurate for samples of wood produced after 1950.

This is because the concentration of carbon-14 in the atmosphere greatly increased due to nuclear weapons testing.

A tree absorbs carbon-14 during its lifetime.

A student suggests that trees grown after 1950 are contaminated with carbon-14.

Give a reason why the student’s suggestion is correct.

Explain how nuclear weapons testing affects the determination of the age of a sample of wood produced after 1950.

Protactinium is an element with several different radioactive isotopes.

Protactinium‑234 has a half‑life of 6.7 hours.

A sample of protactinium‑234 has an initial activity of 800 units.

Give a suitable unit for activity.

On the axes below, sketch a graph for the decay of the sample of protactinium‑234 during its first three half‑lives.

When protactinium‑234 undergoes beta (β^–) decay it becomes uranium‑234.

The incomplete nuclear equation shows this process.

Complete the nuclear equation to show the beta decay of protactinium‑234.

Write your answers in the dashed boxes.

A student suggests an experiment to determine the type of radiation emitted by a different isotope of protactinium, protactinium‑231.

This is the suggested method.

Step 1 connect a suitable radiation detector to a radiation counter

Step 2 place a source of protactinium‑231 at a fixed distance of 3 cm from the radiation detector

Step 3 record the count of detected radiation for a time of one minute

Step 4 place a sheet of paper between the source and detector

Step 5 record the count of detected radiation for a time of one minute

Step 6 repeat Steps 4 and 5 using a sheet of aluminium and then a sheet of lead instead of the sheet of paper

The table shows the results of the investigation when it is done by a teacher.

Which of these is the dependent variable in the investigation?

The student’s method does not allow for background radiation.

Describe how the student’s method should be modified to allow for background radiation.

Describe how the student’s method could be modified to improve the reliability of the results.

Evaluate the data from the experiment to conclude the type of radiation emitted by protactinium‑231.

The photograph shows the nuclear fusion reactor called ITER.

Describe the difference between nuclear fusion and nuclear fission.

At ITER, hydrogen-3 and hydrogen-2 will be fused into helium and another particle labelled X.

Complete the nuclear equation for the fusion of hydrogen-3 and hydrogen-2.

Discuss potential safety advantages of a fusion reactor compared with a fission reactor.

You should refer to the products of this fusion reaction and to the fission reaction of uranium.

The half-life of a radioactive isotope is 12 years.

The activity of a sample of this isotope is 120 kBq.

Calculate the activity of this sample after 48 years.

A material called granite is used as a work surface in a kitchen.

Granite is formed naturally and contains radioactive isotopes.

The granite work surface contributes to the background radiation in the kitchen.

Give another naturally occurring source of background radiation.

Granite contains the isotope thorium‑232 (²³²₉₀Th).

Thorium‑232 decays by a sequence of alpha decays and beta decays to form radon‑220 (²²⁰₈₆Rn).

State two differences between alpha radiation and beta radiation.

The incomplete nuclear decay equation summarises the decay sequence of thorium-232 into radon‑220.

Calculate the number of alpha particles and the number of beta particles emitted in this decay sequence.

Thorium‑232 is a solid and remains in the work surface.

Radon‑220 is a gas and is emitted from the work surface.

Thorium‑232 and radon‑220 both emit alpha radiation.

Discuss the hazards due to the granite work surface when a person is working in the kitchen.

Refer to contamination and irradiation in your answer.

Radon is a radioactive gas that contributes to background radiation.

Describe what is meant by the term background radiation.

The graph shows the activity of a sample of radon‑222.

State what is meant by the term half‑life.

Use the graph to determine the half‑life of radon‑222.

Radon‑222 is formed by multiple alpha decays of uranium‑234.

Complete the nuclear equation by giving the missing information.

Radon‑222 also emits alpha radiation.

Explain the hazard to humans of breathing in air contaminated with radon‑222.

This question is about nuclear fusion.

The incomplete nuclear equation shows the fusion of two isotopes of hydrogen.

Identify particle X in the nuclear equation.

Each fusion reaction releases approximately 310^–12J of energy.

Estimate how many reactions are needed to produce 1 J of energy.

Give your answer to 1 significant figure.

Explain why this fusion reaction will only happen at high temperature and high pressure.

A tokamak is an experimental nuclear fusion reactor.

Strong magnetic fields are used to contain the reactants inside the tokamak.

The diagram shows a positively charged hydrogen nucleus in a uniform magnetic field directed out of the page.

magnetic field out of page

positively charged hydrogen nucleus

The nucleus experiences a force acting to the left because of the magnetic field.

Deduce how the nucleus must behave to experience this force.

Suggest how engineers working on the tokamak could increase the force on the nucleus.

Cobalt‑60 is a radioactive isotope of cobalt.

The table gives the activity of a sample of cobalt‑60 over a period of 10 years.

Give a suitable unit for activity.

The graph shows the data.

Label both axes.

Draw the curve of best fit.

Use the graph to determine the half‑life of cobalt‑60.

Estimate the time taken for the activity to decrease to of its initial value.

Cobalt‑60 decays by beta emission.

Describe what happens to the nucleus of a cobalt‑60 atom during beta decay.

Cobalt‑60 also emits gamma radiation.

Cobalt‑60 is produced in a nuclear reactor.

Discuss the hazards involved and the precautions taken when disposing of cobalt‑60.

In extreme conditions, the isotope lithium-6 can be made to undergo nuclear fission.

The lithium-6 nucleus absorbs a neutron and produces an alpha particle and an isotope of hydrogen.

The incomplete nuclear equation for this fission is

Complete the nuclear equation by writing the numbers in the boxes.

Explain why this fission does not cause a chain reaction.

Explain the difference between nuclear fission and nuclear fusion.

Uranium-235 captures a neutron and undergoes nuclear fission in a chain reaction.

The equation shows a possible nuclear fission reaction.

Calculate x, the number of neutrons released by this fission reaction.

Describe what is meant by a chain reaction.

Iodine-129 is an isotope found in radioactive waste from nuclear power stations.

Iodine-129 has a half-life of approximately 15 million years.

A sample of iodine-129 has an activity of 72 kBq.

Show that the time required for the sample to have an activity less than 5 kBq is approximately 60 million years.

Some radioactive waste from nuclear power stations has a very long half-life.

Discuss precautions that must be taken when disposing of this radioactive waste.

The nuclear equation shows how a nucleus of uranium‑236 may undergo nuclear fission.

Determine how many neutrons are released in this fission process.

The table gives some of the constituents of this nuclear fission.

Complete the table by putting one tick () in each row to show whether the constituent is a parent nucleus or a daughter nucleus.

Describe how the neutrons released in this fission process can cause a chain reaction.

This question is about a nuclear fission chain reaction.

Uranium-235 is an isotope of uranium that can undergo nuclear fission.

The table gives some statements about this fission process.

Add ticks (✓) to the table to show which statements are correct.

State which product of nuclear fission causes the next uranium-235 nucleus to split in the chain reaction.

Uranium-235 is radioactive and emits alpha radiation.

Which of these statements describes alpha radiation?

Some of the products of nuclear fission are radioactive because their nuclei have too many neutrons.

These nuclei become more stable when a neutron changes into a proton.

State which type of radiation is emitted by radioactive nuclei with too many neutrons.

Technetium-98 and technetium-99 are isotopes of the element technetium.

Describe the difference between the nuclei of technetium-98 and technetium-99

Technetium-99 is formed when the element molybdenum-99 decays.

Complete the nuclear equation for the decay of molybdenum into technetium-99

Describe an experiment that a scientist could use to demonstrate that the emission from technetium-99 is gamma radiation.

Include details of a safety precaution in your answer.

A scientist measures the count rate at different distances from the technetium source.

The graph shows how the count rate changes with distance from the technetium source.

The scientist suggests that the relationship between the count rate and distance is (distance)² × count rate constant

Use data from the graph to determine whether these results support this relationship.

The photograph shows a glass plate made from uranium glass.

Uranium oxide is used to give the glass a green colour.

State what information the numbers 92 and 238 give about the nucleus of this isotope of uranium.

Uranium‑238 decays by alpha emission.

Describe how the nucleus of a uranium‑238 atom changes as a result of alpha emission.

The table gives some information about the uranium glass plate.

Calculate the number of uranium‑238 atoms in the plate.

Uranium‑238 is an alpha emitter and has a half‑life of 4.5 billion years.

Explain why it is safe to eat food from the uranium glass plate.