Pearson Edexcel GCSE Combined Science · P6

Radioactivity

50 revision questions with answers for P6 Radioactivity in Pearson Edexcel GCSE Combined Science (spec 1SC0). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below. Not official Pearson material.

All 50 questions and answers

Question 1 · Spec P6.1
Describe an atom's mass and charge distribution.
Answer:
Almost all mass lies in a tiny positive nucleus; negative electrons occupy the much larger surrounding region.
Question 2 · Spec P6.2
What is the typical order of magnitude of an atom's diameter?
Answer:
About 10⁻¹⁰ m, with a much smaller nucleus.
Question 3 · Spec P6.4
What are isotopes?
Answer:
Atoms of the same element with the same proton number but different neutron numbers.
Question 4 · Spec P6.3
What do atomic number and mass number represent?
Answer:
Atomic number counts protons; mass number counts protons plus neutrons.
Question 5 · Spec P6.3
A nucleus has A = 23 and Z = 11. How many neutrons?
Answer:
23 − 11 = 12.
Question 6 · Spec P6.5
State proton, neutron and electron charges.
Answer:
+1, 0 and -1 respectively.
Question 7 · Spec P6.5
What are a positron's relative charge and mass?
Answer:
Charge +1; mass equal to an electron's, about 1/1836 of a proton's.
Question 8 · Spec P6.6
Why is a neutral atom uncharged?
Answer:
Its proton and electron numbers are equal.
Question 9 · Spec P6.7
How are electron distances from the nucleus restricted?
Answer:
Electrons occupy particular allowed shells or energy levels.
Question 10 · Spec P6.8
What can happen when an electron absorbs radiation?
Answer:
It can move to a higher energy level farther from the nucleus.
Question 11 · Spec P6.8
What happens when an electron moves to a lower energy level?
Answer:
Electromagnetic radiation is emitted.
Question 12 · Spec P6.9
How can an atom become a positive ion?
Answer:
By losing one or more outer electrons.
Question 13 · Spec P6.10
What causes nuclear radiation, and why is decay random?
Answer:
Unstable nuclei decay; the exact decay time of an individual nucleus cannot be predicted.
Question 14 · Spec P6.15
What is an alpha particle?
Answer:
Two protons and two neutrons, equivalent to a helium nucleus.
Question 15 · Spec P6.18
What happens during beta-minus decay?
Answer:
A neutron changes into a proton and an electron; the electron is emitted.
Question 16 · Spec P6.19
What happens during beta-plus decay?
Answer:
A proton changes into a neutron and a positron; the positron is emitted.
Question 17 · Spec P6.15
What is gamma radiation?
Answer:
Electromagnetic radiation emitted from a nucleus.
Question 18 · Spec P6.10
What other uncharged nuclear particle can be emitted?
Answer:
A neutron.
Question 19 · Spec P6.11
What does ionising radiation do?
Answer:
It transfers enough energy to remove electrons from atoms, forming ions.
Question 20 · Spec P6.16
Compare alpha, beta and gamma penetration.
Answer:
Alpha is stopped by paper; beta by thin aluminium; gamma needs thick lead or concrete for substantial reduction.
Question 21 · Spec P6.16
Compare their ionising powers.
Answer:
Alpha is most strongly ionising, beta intermediate and gamma less ionising per path length.
Question 22 · Spec P6.12
What is background radiation?
Answer:
Ionising radiation continually present in the environment, apart from the particular source being investigated.
Question 23 · Spec P6.13
Name natural background-radiation sources.
Answer:
Radioactive rocks and radon, cosmic radiation and naturally occurring isotopes in living organisms.
Question 24 · Spec P6.13
Name a human-related source of radiation exposure.
Answer:
Medical X-rays or radioactive materials used in medicine; sources vary with individual circumstances.
Question 25 · Spec P6.14
How can photographic film detect radiation?
Answer:
Exposure changes the film, producing darkening when developed.
Question 26 · Spec P6.14
How does a Geiger-Muller system record radiation?
Answer:
Ionisation in the detector produces pulses counted electronically.
Question 27 · Spec P6.17
Describe the plum pudding model.
Answer:
Electrons embedded in a diffuse positive sphere, without a small central nucleus.
Question 28 · Spec P6.17
What did most alpha particles do in Rutherford's scattering experiment?
Answer:
They passed through the foil, showing that most of an atom is empty space.
Question 29 · Spec P6.17
What did rare large deflections reveal?
Answer:
A tiny dense positive nucleus contains most atomic mass.
Question 30 · Spec P6.17
How did Bohr develop the nuclear model?
Answer:
He proposed electrons occupying specific allowed energy levels.
Question 31 · Spec P6.20
How does alpha decay change A and Z?
Answer:
A decreases by 4 and Z by 2.
Question 32 · Spec P6.20
How does beta-minus decay change A and Z?
Answer:
A stays constant and Z increases by 1.
Question 33 · Spec P6.20
How does beta-plus decay change A and Z?
Answer:
A stays constant and Z decreases by 1.
Question 34 · Spec P6.20
How does neutron emission change A and Z?
Answer:
A decreases by 1 while Z stays unchanged.
Question 35 · Spec P6.21
Why may gamma emission follow another nuclear decay?
Answer:
The daughter nucleus releases excess energy by rearranging; gamma emission changes neither mass number nor proton number.
Question 36 · Spec P6.22
A nucleus has A = 210 and Z = 84 before alpha decay. Find daughter values.
Answer:
A = 206 and Z = 82.
Question 37 · Spec P6.22
A nucleus has A = 22 and Z = 11 before beta-plus decay. Find daughter values.
Answer:
A = 22 and Z = 10.
Question 38 · Spec P6.23
How does a radioactive sample's activity change over time?
Answer:
It decreases as fewer undecayed unstable nuclei remain.
Question 39 · Spec P6.24
What does one becquerel mean?
Answer:
One decay per second.
Question 40 · Spec P6.25
Define half-life.
Answer:
Time for half the undecayed nuclei to decay, or for source activity to halve.
Question 41 · Spec P6.26
Why can half-life predict a large sample but not one nucleus's decay time?
Answer:
Many random events form a predictable statistical pattern, while each individual decay remains unpredictable.
Question 42 · Spec P6.27
A source falls from 640 to 320 Bq in 8 hours. Find half-life.
Answer:
8 hours.
Question 43 · Spec P6.27
What fraction remains after three half-lives?
Answer:
1/2³ = 1/8, or 12.5%.
Question 44 · Spec P6.27
A sample has half-life 5 min. How much of an initial 80 g isotope remains after 10 min?
Answer:
Two half-lives pass: 80 → 40 → 20 g.
Question 45 · Spec P6.27
Why subtract background before analysing a source's count-rate decay?
Answer:
Background does not decay with the source and otherwise distorts the apparent halving.
Question 46 · Spec P6.29
Why can ionising radiation damage tissue or cause cancer?
Answer:
It can damage cell structures and DNA; mutations may lead to uncontrolled cell division.
Question 47 · Spec P6.31
How can exposure to a radioactive source be reduced?
Answer:
Reduce time, increase distance and use suitable shielding and remote handling.
Question 48 · Spec P6.31
Why do medical radiation procedures limit patient and staff doses?
Answer:
To obtain useful diagnosis or treatment while reducing unnecessary tissue exposure.
Question 49 · Spec P6.32
Distinguish contamination and irradiation.
Answer:
Contamination is radioactive material on or inside something; irradiation is exposure to radiation from a source.
Question 50 · Spec P6.32
Why can contamination remain hazardous after leaving the original source?
Answer:
The contaminating atoms remain and continue to decay; irradiation ends when exposure to the external source ends.

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