AQA GCSE Physics

Topic Questions

GCSEPhysicsAQATopic Questions4. Atomic Structure4.2 Atoms & Nuclear Radiation

4.2 Atoms & Nuclear Radiation

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1a1 mark

State the definition of half-life.

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1b1 mark

The half‐life of Cobalt‐60 is 5 years.

The count‐rate of a sample of Cobalt‐60 is 100 counts per minute.

State how many half-lives there are in 10 years.

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1c2 marks

Higher Only

Calculate the count‐rate of the Cobalt‐60 after 10 years.

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1d3 marks

A radioactive isotope can be used as a tracer in a patient’s body. It is monitored by a radiation detector outside the body.

Four possible radioactive isotopes are shown in Table 1

Table 1

Radioactive isotope Type of radiation emitted Half-life
Radon‐222 Alpha 3.8 days
Iodine‐131 Gamma 8 days
Cobalt‐60 Gamma 5 years
Americium-241 Alpha 470 years

 

Which radioactive isotope from the table is best to use as a medical tracer?

Explain your answer.

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2a2 marks

Carbon-14 is a radioactive isotope of carbon.

It has the symbol

7-1-mcq-q6-question

When carbon-14 decays it emits a beta particle.

State the nature of a beta particle.

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2b2 marks

An iodine isotope I presubscript 53 presuperscript 135 decays beta emission. The daughter particle is an isotope of xenon (Xe).

State the number of each type of particle in a neutral atom of I presubscript 53 presuperscript 135.

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2c2 marks

Complete the decay equation for iodine-135:

  straight I presubscript 53 presuperscript 135 space rightwards arrow space straight beta presubscript... end presubscript presuperscript... end presuperscript space plus space Xe presubscript... end presubscript presuperscript... end presuperscript

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2d4 marks

A factory makes baking paper. In order to keep the baking paper the same thickness, beta radiation is passed through the paper.

A Geiger counter on the other side of the paper measures how much radiation passes through the paper and the rollers change the thickness of paper accordingly as shown in Figure 1.

Figure 1

 

beta-thickness-monitoring

Explain why alpha and gamma radiation are not used for this process.

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3a1 mark

People who work with ionising radiation need to measure the amount of radiation they are exposed to. For many years, a film badge was used to detect the radiation.

State the name of another device that can be used to detect alpha radiation.

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3b4 marks

A student records the following data in a table when using this device on two radioactive sources for the same amount of time.

Complete the table, including the unit for activity

   
Source Recorded Activity (..........) Background Activity (..........) Corrected Activity (..........)
Radium 104   100
Americium 25    

     

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3c3 marks

Higher Tier Only

The half-life of the radium isotope is 30 days. Calculate the activity from the radium source from part (b) after 60 days.

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3d2 marks

Another source has an initial activity of A0. This is shown in Figure 1.

Figure 1
4-2-e-3d-activity-graph

Use Figure 1 to determine the half-life of the source. 

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4a4 marks

Some atomic nuclei are unstable. 

Complete the sentences about radioactive decay. 

Choose answers from the box. 

Each answer can be used once, more than once or not at all.

reducing protons radiation molecules
random
 neutrons
 planned visible light

     

Some isotopes are unstable because of their large size or because they have too many or too few .................... .

Unstable nuclei can emit .................... to become more stable.

As this moves away from the nucleus, it takes some energy with it .................... the overall energy of the nucleus and making the nucleus more stable.

Radioactive decay is a .................... process. This means it is not possible to know exactly when a particular nucleus will decay.

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4b3 marks

Draw a straight line from each description to the type of radiation it describes.

 

7-1-sqs-q6new-question

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4c2 marks

Define contamination and irradiation.

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4d7 marks

The following statements are about contamination or irradiation. 

  1. Prevented by safe handling of sources and airtight safety clothing
  2. Object is exposed to radiation but does not become radioactive
  3. Caused by inhalation or ingestion of radioactive sources
  4. Danger from radiation emitted within the object
  5. Danger is from radiation emitted outside the object
  6. Caused by presence of radioactive sources outside the body
  7. Prevented by using shielding, such as lead clothing
  8. Object becomes radioactive and emits radiation

Complete Table 1 to indicate whether the statement is about contamination or irradiation. The first sentence has been done for you.

Table 1

Irradiation Contamination
 

1. Prevented by safe handling of sources and airtight safety clothing
   
   
   

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1a3 marks

A sample of sodium-24 has an activity of 1400 Bq. The half-life of sodium-24 is 15 hours.

Sketch a graph on the axes in Figure 1 to show how the activity of this sample changes over the next 40 hours.
4-2-h-1a-activity-graph
Figure 1

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1b4 marks

Granite is a rock which contains a radioactive isotope of uranium that decays over a long period of time. 

Explain how scientists can use this radioactivity to find the age of a piece of granite.

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1c2 marks

Higher Only

Suggest why the age of a piece of granite could not be found using a uranium isotope with a half-life of 15 hours.

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2a3 marks

Higher Only

Figure 1 shows the number of neutrons and the number of protons in some isotopes formed during successive radioactive decays.

Figure 1

4-2-h-2a-radioactive-decay-grid

Define the term isotope, and explain why some isotopes can be described as stable

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2b2 marks

Describe what happens to the number of protons and the number of neutrons when a nucleus of Pb presubscript blank presuperscript 210 decays to form Bi presubscript blank presuperscript 210.

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2c2 marks

Explain why the mass number and the atomic number do not change when a gamma ray is emitted from a nucleus.

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3a3 marks

Radon-222 is radioactive. It can be represented as Rn presubscript 86 presuperscript 222.

State the number of protons, the number of neutrons and the number of electrons for a neutral atom of radon-222.

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3b2 marks

Extended

Decay of a radon-222 nucleus is by α-particle emission. The element formed is polonium (Po).

 

Complete the equation for the decay of radon-222.

 
Rn presubscript 86 presuperscript 222 rightwards arrow

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3c3 marks

Higher Only

Radon-222 has a half-life of 3.8 days.

At a certain time, a sample contains 6.4 × 106 radon nuclei.

Calculate the number of α-particles emitted by the radon nuclei in the following 7.6 days.

 

number of  α-particles emitted = ...........................................................

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3d1 mark

Discuss the meaning and benefits of peer-reviewed research.

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1a1 mark

Household smoke alarms use alpha radiation sources to detect smoke.

Figure 1 shows how a smoke alarm works.

Figure 1

fig-1-4-2-medium-aqa-gcse-physics

The smoke alarm does not sound while alpha radiation is detected by the detector. 

Explain why the alarm sounds when smoke particles enter the casing.

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1b1 mark

Why is using an alpha emitter in a smoke alarm safe to use in a house?  

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1c2 marks

Explain why the smoke alarm would not work if the alpha source were replaced by a beta or gamma source.

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1d2 marks

Figure 2 shows how the count rate from the alpha source in the smoke alarm varies with time.

Figure 2

half-life-fixed

Calculate the half life of the alpha source in the smoke alarm.

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1e2 marks

Explain why it is an advantage for the alpha emitter in the smoke alarm to have a long half life.

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2a1 mark

Of the three types of radiation, alpha (α), beta (β) and gamma (γ), which two will pass through a sheet of paper?

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2b1 mark

Which two types of radiation will be deflected by a magnetic field?

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2c1 mark

Which type of radiation has the shortest range in air?

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2d1 mark

A student suggests that the halflife of a radioactive source could be decreased by heating it in a Bunsen burner. The student thinks that this would speed up the radioactive decays, and make it decay more quickly.

Suggest why the student is wrong.

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2e1 mark

Protactinium-234 is a radioactive isotope that is often used in school science experiments. It emits beta radiation.

How is an atom of protactinium-234 different to the isotope protactinium-236?

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2f2 marks

Figure 3 shows how the count rate of a sample of protactinium-234 changes with time.

Figure 3

fig-3-4-2-medium-aqa-gcse-physics

Use the graph to calculate the halflife of protactinium-234

Show clearly how you used the graph to obtain your answer.

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3a4 marks

Table 1 shows how the activity of a sample of plutonium-238 varies with time.

Table 1

Time in years 0 50 100 150 200 250
Activity in Bq 980 660 450 305 205 140

Plot a graph of activity (y-axis) against time (x-axis).

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3b1 mark

Add a curve of best fit to your data

q3b-4-2-medium-aqa-gcse-physics

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3c2 marks

Use your graph to determine the halflife of plutonium-238.

Show your working.

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3d2 marks

Plutonium-238 can be used as a power source for a radioisotope thermoelectric generator (RTG).

The thermal energy produced by the plutonium-238 is converted to electrical energy to power spacecraft.

The Cassini space probe was powered with such a device.

Figure 4 shows what an RTG looks like. The radioactive sources are inside the metal container.

Figure 4

fig-4-4-2-medium-aqa-gcse-physics

Plutonium-238 is an alpha emitter.

Explain why it is safe for scientists to handle RTG units without protective clothing.

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4a1 mark

An atom of the isotope tungsten-183 emits an alpha particle and decays into an atom of hafnium.

An alpha particle is the same as a helium nucleus. State the symbol and notation used to represent an alpha particle in nuclear equations.

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4b2 marks

How many protons and how many neutrons are there in an alpha particle?

Number of protons = _________

Number of neutrons = ________

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4c2 marks

The equation below represents the decay of tungsten-183.

Complete the equation by writing the correct number in each of the two boxes.

W presubscript 74 presuperscript 184 space rightwards arrow space Po presubscript ▭ presuperscript ▭ space plus space alpha space particle

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4d1 mark

Atoms of the isotope iodine-128 decay by emitting a beta particle.

State the symbol and notation used to represent a beta particle in nuclear equations.

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4e2 marks

Beta decay does not cause the mass number of an atom to change.

Explain why not.

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4f2 marks

The equation representing the decay of iodine-128 to xenon is shown below.

Complete the equation by writing the correct number in each of the two boxes.

straight I presubscript 53 presuperscript 128 space space rightwards arrow space Xe presubscript ▭ presuperscript ▭ space plus space beta space particle

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4g2 marks

If Iodine-128 were to decay via alpha decay instead of via beta decay, it would produce a different element to xenon.

Explain why.

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4h1 mark

There is a possibility that iodine-128 can emit a gamma ray.

State the change(s) to the nucleus that would occur if iodine-128 emitted a gamma ray.

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5a2 marks

Figure 5 shows how gamma radiation can be used to irradiate food stored in a wooden box.

The radiation kills bacteria on the food.

Figure 5

fig-5-4-2-medium-aqa-gcse-physics

Explain why gamma radiation, rather than alpha radiation is used to kill bacteria on the food.

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5b2 marks

The box has this label:

q5b-4-2-medium-aqa-gcse-physics

Explain why food which has been irradiated with gamma radiation is safe to eat.

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5c2 marks

Explain why foods which had been contaminated with an alpha emitter would not be safe to eat.

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