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IGCSEPhysics: Co-ordinated Sciences (Double Award)CIEExam Questions5. Nuclear PhysicsRadioactivity

Radioactivity (CIE IGCSE Physics: Co-ordinated Sciences (Double Award))

Exam Questions

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Radioactivity

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Radioactivity

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1a3 marks

The isotope hydrogen-1 has a proton number of 1 and a nucleon number of 1.

 
Two isotopes of helium are helium-3 and helium-4.

 
Helium-3 has a proton number of 2 and a nucleon number of 3.

 
Helium-4 has a nucleon number of 4.

 
Complete Table 11.1 for neutral atoms of these isotopes of helium.

   table3

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1b3 marks

An experiment takes place in a laboratory shielded from all background radiation. A sample of radioactive material is wrapped in aluminium foil of thickness 0.1 mm. A detector of ionising radiation placed 1 cm from the foil records a reading.


A piece of aluminium of thickness 5 mm is placed between the detector and the foil. The detector reading drops to zero.

 
State and explain any type of radiation passing through the aluminium foil.

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2a1 mark

Radioactive sources emit α-(alpha), β-(beta) and γ-(gamma) radiations.

 

State which of these types of radiation can pass through paper.

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2b1 mark

Barium-137 is a radioactive isotope. The nuclide notation for barium-137 is

 
B presubscript 56 presuperscript 137 a
 

Determine the number of neutrons in a nucleus of barium-137.

 
 
number of neutrons = ........................................................

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2c3 marks

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

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3a3 marks

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

For a neutral atom of radon-222, state

 
1. the number of protons, ...........................
 
2. the number of neutrons, ...........................
 
3. the number of electrons. ...........................

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3b2 marks

Extended tier only

A radon-222 nucleus decays by α-particle emission to a polonium (Po) nucleus.

 

Complete the equation for the decay of radon-222.

 
Rn presubscript 86 presuperscript 222 rightwards arrow

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3c3 marks

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 = ...........................................................

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4a3 marks

The nuclide notation space presubscript straight Z presuperscript straight A straight X describes the nucleus of one type of atom.
Draw a line from each symbol to the correct description for that symbol.

q12a

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4b6 marks
(i)

One radioactive isotope has a half-life of 6.0 years.

A sample of this isotope has a mass of 12 mg.

Calculate the mass of this isotope that remains in the sample after 18 years.

 

 

mass remaining = .................................................... mg [3]

(ii)

The sample decays by emitting a β-particle.

Describe the nature of a β-particle.

 [2]

(iii)

Describe how the nucleus of the isotope changes due to the emission of a β-particle.

 [1]

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5a2 marks

Extended tier only

A radioactive nucleus of uranium-235 decays to a nucleus of thorium and emits an α-particle.
Complete the equation.

VnHpZL5z_q11a

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5b5 marks

A nucleus of uranium-235 undergoes nuclear fission in a reactor.

 
(i)
State what is meant by nuclear fission.
[1]
 
(ii)
Suggest why a nuclear reactor is surrounded by thick concrete walls.
[2]
 
(iii)

State one environmental advantage and one environmental disadvantage of using a fission reactor to generate electrical energy in a power station.

[2]

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5c3 marks

The thorium produced by the decay in (a) is also radioactive and has a half-life of 26 hours.

At a certain time, a pure sample of this isotope initially contains 4.8 × 109 atoms.

Calculate the number of atoms of this sample that decay in the following 52 hours.

 

 

number = ...........................................................

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14 marks

Fig.12.1 shows a radioactive source placed close to a radiation detector and counter. The detector can detect α, β and γ radiation.

feb-march-2018-32-q12

The radioactive source emits β-particles only.

 
Describe how you could show that the source emits β-particles only.
As part of your answer, you may draw on Fig.12.1 and add any other apparatus you may need.

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2a1 mark
A teacher carries out two experiments at the same time.
 

In the first experiment the count rate for a sample of a radioactive isotope is measured every 30 seconds for 6 minutes.


The results are shown in Table 12.1.

screenshot-2022-10-14-at-09-35-36

Estimate the half-life of the radioactive isotope. Use the information in the table.

 
half-life = ...................................................... minutes 

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2b1 mark

In the second experiment the teacher repeats the procedure with another sample of the same radioactive isotope. The mass of the second sample is greater than that of the first sample.

 
Suggest a value for the count rate for this sample at the start of the experiment.

 
count rate = ...................................................... counts/second

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2c3 marks

One type of particle emitted during radioactive decay is an α-particle (alpha particle).

Describe:

  
(i)
the nature of an α-particle

[1]

(ii)
the ionising ability of an α-particle

[1]

(iii)
the penetrating ability of an α-particle.

[1]

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3a2 marks
A radioactive substance decays by emitting an α-particle.
   

The nuclide notation for an α-particle is

   
straight alpha presubscript 2 presuperscript 4
    
(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]

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3b4 marks

Fig. 12.1 shows the decay curve for a radioactive material.

  
screenshot-2022-10-20-at-12-11-24
  
(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]

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4a4 marks

Astatine-210 is a radioactive material. The nucleus of astatine can be represented by the symbol shown.

A presubscript 85 presuperscript 210 t

Complete the table to describe the nucleus of astatine-210.

 
type of particle number of particles charge on particle
neutron    
    positive

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4b5 marks

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.
 
cie-2019-18
[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]

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