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Science questions, chapter 8
Nama / NameKelas / ClassTarikh / Date

Radioactivity

43 marks. Use Practice to check each answer as you go, or Exam to answer everything against the clock first.

Section A: objective questions

12 marks
Choose the best answer for each question.
1

Question 1

Who discovered X-rays in 1895?
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B
Wilhelm Roentgen discovered X-rays in 1895. Becquerel discovered radioactivity in 1896.
For the teacher: Remembering, low difficulty, standard 8.1.1
Textbook p. 232
2

Question 2

Marie and Pierre Curie extracted two radioactive elements from pitchblende. What were the elements?
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D
From the uranium ore pitchblende the Curies extracted polonium and radium.
For the teacher: Remembering, low difficulty, standard 8.1.1
Textbook p. 233
3

Question 3

Which statement describes radioactive decay?
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A
Radioactive decay is the random and spontaneous process where an unstable nucleus emits radioactive radiation until it is more stable.
For the teacher: Understanding, low difficulty, standard 8.1.1
Textbook p. 234
4

Question 4

What is the S.I. unit of radioactivity?
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C
The S.I. unit of radioactivity is the becquerel (1 decay per second). The curie is an older unit and the sievert measures dose.
For the teacher: Remembering, low difficulty, standard 8.1.2
Textbook p. 235
5

Question 5

The half-life of Pa-234 is 5.2 hours. What mass of a 160 g sample remains after 15.6 hours?
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B
15.6 ÷ 5.2 = 3 half-lives. 160 → 80 → 40 → 20 g.
For the teacher: Applying, low difficulty, standard 8.1.2
Textbook p. 235
6

Question 6

Diagram 1 shows the activity of radioactive substance R against time. What is the half-life of R?
Graph of activity against time: 640 Bq at 0 min, 320 Bq at 6 min, 160 Bq at 12 min, 80 Bq at 18 min, 40 Bq at 24 min
Diagram 1
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A
Half of 640 Bq is 320 Bq, which is reached at 6 minutes.
For the teacher: Applying, low difficulty, standard 8.1.2
Textbook p. 236
7

Question 7

Which particles are found in the nucleus of an atom?
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C
The nucleus contains protons (positive) and neutrons (neutral). Electrons move around the nucleus.
For the teacher: Remembering, low difficulty, standard 8.2.1
Textbook p. 238
8

Question 8

A particle has 13 protons and 10 electrons. Which statement is correct?
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D
Charge = +13 − 10 = +3. It has lost three electrons, so it is a positive ion.
For the teacher: Applying, medium difficulty, standard 8.2.2
Textbook p. 239
9

Question 9

Which of the following is a non-ionising radiation?
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A
Radio waves are non-ionising. X-rays, gamma rays and alpha radiation are ionising.
For the teacher: Understanding, low difficulty, standard 8.3.1
Textbook p. 240
10

Question 10

Diagram 2 shows radiation from a source passing between two charged plates. Which statement is correct?
Alpha bends towards the negative plate, gamma goes straight, beta bends towards the positive plate
Diagram 2
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B
Opposite charges attract. Beta bends to the positive plate, so it is negative. Alpha bends to the negative plate, so it is positive. Gamma is not deflected because it is neutral.
For the teacher: Analysing, medium difficulty, standard 8.3.2
Textbook p. 241
11

Question 11

A radioactive source is placed behind a sheet of paper. A detector in front of the paper records almost no radiation. Which radiation does the source emit?
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C
Beta and gamma pass through paper, so the detector would still record them. Only alpha is stopped by paper, so the source emits alpha only.
For the teacher: Analysing, medium difficulty, standard 8.3.2
Textbook p. 241
12

Question 12

Which radiation is used to preserve fruits by killing bacteria?
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D
Gamma rays are used in food preservation; the food carries the Radura logo.
For the teacher: Remembering, low difficulty, standard 8.4.1
Textbook p. 248

Section B: structured questions

31 marks
Answer all questions.
13

Question 13

Radioactivity was discovered in 1896 and studied further by Marie and Pierre Curie.
[1 mark] (a)Name the scientist who first discovered radioactivity.
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[1 mark] (b)Becquerel left a uranium compound near a photographic plate. State what he observed.
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[1 mark] (c)Marie and Pierre Curie detected radioactive radiation by another property. State this property.
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For the teacher: Remembering, low difficulty, standard 8.1.1
Textbook p. 233
14

Question 14

A radioactive substance has a half-life of 4 days. The original mass of the sample is 64 g.
[1 mark] (a)What is meant by half-life?
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[2 marks] (b)Calculate the mass of the substance that remains after 12 days.
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For the teacher: Applying, low difficulty, standard 8.1.2
Textbook p. 235
15

Question 15

Diagram 3 shows the activity of radioactive substance S against time.
Graph of activity against time: 160 Bq at 0 min, 113 Bq at 10 min, 80 Bq at 20 min, 57 Bq at 30 min, 40 Bq at 40 min
Diagram 3
[2 marks] (a)Use the graph to find the half-life of S. Show how you obtained your answer.
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[1 mark] (b)Predict the activity of S at 60 minutes.
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For the teacher: Analysing, medium difficulty, standard 8.1.2
Textbook p. 236
16

Question 16

Table 1 shows the subatomic particles in particle X.
ParticleProtonsNeutronsElectrons
X8810
[1 mark] (a)Is X a positive ion or a negative ion?
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Tick each point you got.
[2 marks] (b)Explain your answer in (a).
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[1 mark] (c)State the charge on X.
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For the teacher: Understanding, low difficulty, standard 8.2.2
Textbook p. 239
17

Question 17

Choose the correct radiation for each description.
[1 mark] (a)The radiation with the highest ionising power.
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Alpha
[1 mark] (b)The radiation that needs thick lead to stop it.
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Gamma
[1 mark] (c)A high-speed electron.
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Beta
[1 mark] (d)The radiation that is not deflected by an electric field.
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Gamma
For the teacher: Understanding, low difficulty, standard 8.3.2
Textbook p. 241
18

Question 18

A television gives a dose rate of ionising radiation of 0.01 mSv/h. Anis watches television for 3 hours every day for 4 days.
[2 marks] (a)Calculate the total dose she receives from the television.
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[1 mark] (b)A Geiger counter shows a background radiation of 0.15 μSv/h in her garden. Is this safe? Give a reason.
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[1 mark] (c)State one way to reduce the radiation she receives from the television.
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Any 1 points
Tick each point you got.
For the teacher: Applying, medium difficulty, standard 8.3.3
Textbook p. 244
19

Question 19

Archaeologists find a wooden tool. Its carbon-14 activity is one eighth of the activity in a living tree. The half-life of C-14 is 5 700 years.
[1 mark] (a)How many half-lives have passed?
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[2 marks] (b)Calculate the age of the tool.
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[1 mark] (c)Name the radiation emitted when C-14 decays.
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For the teacher: Analysing, medium difficulty, standard 8.4.1
Textbook p. 247
20

Question 20

A hospital stores waste from cancer treatment, which gives out gamma rays.
[1 mark] (a)Why is the waste kept in containers with thick lead walls?
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[2 marks] (b)A technician suggests using a 3 mm aluminium box instead because it is lighter. Evaluate this suggestion.
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For the teacher: Evaluating, high difficulty, standard 8.4.2
Textbook p. 249
21

Question 21

A factory makes thin sheets of aluminium. The sheets must have a fixed thickness. Suggest how beta radiation can be used to monitor the thickness.
[1 mark] (a)Draw a labelled diagram or describe the arrangement of the source, the sheet and the detector.
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[2 marks] (b)Explain how the device shows that a sheet is too thin.
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For the teacher: Creating, high difficulty, standard 8.4.1
Textbook p. 247