Course: Combined Science + Separate Physics | 20 questions | ← All quizzes
Write A, B, C or D for each question, then tap Show answer to mark it.
Q1 (F, recall) What is the relative charge of a neutron?
A. +1
B. 0
C. −1
D. +2
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✅ B. 0
Protons are +1, electrons are −1 and neutrons have no charge.
Q2 (F, recall) What is the approximate radius of an atom?
A. 1 × 10⁻¹⁴ m
B. 1 × 10⁻⁵ m
C. 1 × 10⁻³ m
D. 1 × 10⁻¹⁰ m
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✅ D. 1 × 10⁻¹⁰ m
The nucleus is about 10 000 times smaller, with a radius of about 1 × 10⁻¹⁴ m.
Q3 (F, definition) What are isotopes?
A. Atoms of the same element with different numbers of neutrons
B. Atoms of different elements with the same mass number
C. Atoms that have gained or lost electrons
D. Atoms with different numbers of protons
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✅ A
Isotopes have the same number of protons (same atomic number) but a different number of neutrons (different mass number).
Examiner tip: C describes an ion.
Q4 (F, recall) What is an alpha particle made of?
A. A high-speed electron
B. An electromagnetic wave
C. Two protons and two neutrons
D. A single neutron
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✅ C
This is the same as a helium nucleus. A is a beta particle and B is gamma radiation.
Q5 (F, recall) Which type of radiation is stopped by a sheet of paper?
A. Alpha
B. Beta
C. Gamma
D. All three
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✅ A. Alpha
Beta is stopped by a few millimetres of aluminium; gamma is only reduced by thick lead or concrete.
Q6 (F, definition) What is the half-life of a radioactive isotope?
A. Half the time it takes for all the nuclei to decay
B. The time it takes for the number of unstable nuclei in a sample to halve
C. The time it takes for the mass of the source to halve
D. Half the time the source is dangerous for
Show answer
✅ B
It can also be defined as the time for the count rate (or activity) to fall to half its initial level.
Examiner tip: the mass of the sample hardly changes, so C is wrong.
Q7 (F/H, calculation) A source has an activity of 1200 Bq and a half-life of 3 hours. What is its activity after 9 hours?
A. 400 Bq
B. 300 Bq
C. 0 Bq
D. 150 Bq
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✅ D. 150 Bq
Number of half-lives = 9 ÷ 3 = 3
1200 → 600 → 300 → 150 Bq
Examiner tip: 400 Bq comes from dividing by 3 instead of halving three times.
Q8 (F/H, calculation) Carbon-14 has an atomic number of 6. How many neutrons are in its nucleus?
A. 6
B. 14
C. 8
D. 20
Show answer
✅ C. 8
Neutrons = mass number − atomic number = 14 − 6 = 8
Q9 (F/H, application) In the alpha particle scattering experiment, most alpha particles passed straight through the gold foil. What did this show?
A. Most of the atom is empty space
B. The nucleus is positively charged
C. Electrons are in shells
D. Atoms are solid spheres
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✅ A
A few particles were deflected (showing a positive nucleus) and very few bounced back (showing the mass is concentrated in a tiny nucleus). This replaced the plum pudding model with the nuclear model.
Q10 (F/H, recall) Which scientist provided the evidence for the existence of neutrons?
A. Rutherford
B. Bohr
C. Thomson
D. Chadwick
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✅ D. Chadwick
Thomson discovered the electron (plum pudding model), Rutherford the nucleus, and Bohr the electron shells.
Q11 (F/H, application) What happens to a nucleus when it emits a beta particle?
A. Its mass number falls by 4 and its atomic number falls by 2
B. Its mass number stays the same and its atomic number increases by 1
C. Nothing changes
D. Its mass number increases by 1
Show answer
✅ B
A neutron turns into a proton and a high-speed electron, which is emitted. A describes alpha decay; C describes gamma emission.
Q12 (F/H, calculation) Radium-226 (atomic number 88) decays by emitting an alpha particle. What is the new nucleus?
A. Mass number 226, atomic number 89
B. Mass number 224, atomic number 86
C. Mass number 222, atomic number 86
D. Mass number 222, atomic number 90
Show answer
✅ C
Mass number: 226 − 4 = 222
Atomic number: 88 − 2 = 86 (radon)
Examiner tip: check the top and bottom numbers balance on both sides of the equation.
Q13 (F/H, application) Which of these is an example of radioactive contamination?
A. Having an X-ray at the dentist
B. Standing near a gamma source
C. Food being irradiated to kill bacteria
D. Radioactive dust landing on your skin
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✅ D
Contamination is when radioactive atoms get onto or into an object. Irradiation is being exposed to radiation from outside, which doesn’t make the object radioactive.
Q14 (F/H, graph) A graph of activity against time for a source shows: 800 Bq at 0 days, 400 Bq at 5 days, 200 Bq at 10 days. What is the half-life?
A. 5 days
B. 10 days
C. 2.5 days
D. 400 days
Show answer
✅ A. 5 days
The activity halves (800 → 400) every 5 days.
Examiner tip: on a curve, read the time for the activity to halve from any starting value. It is always the same.
Q15 (H, calculation) The activity of a source falls from 640 Bq to 80 Bq. What is the net decline, expressed as a ratio of final to initial activity?
A. 1 : 4
B. 1 : 8
C. 1 : 3
D. 8 : 1
Show answer
✅ B. 1 : 8
80 : 640 = 1 : 8
This is 3 half-lives: 640 → 320 → 160 → 80.
Examiner tip: 1 : 3 confuses the number of half-lives with the ratio.
Q16 (F/H, recall) What happens when an electron in an atom absorbs electromagnetic radiation?
A. It leaves the nucleus
B. It turns into a proton
C. It moves to a higher energy level, further from the nucleus
D. It moves closer to the nucleus
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✅ C
If it drops back to a lower energy level, it emits electromagnetic radiation.
Q17 (F/H, recall) An atom loses an outer electron. What does it become?
A. A positive ion
B. A negative ion
C. An isotope
D. A neutron
Show answer
✅ A. A positive ion
It now has more protons than electrons. This process is called ionisation.
Q18 (S only, recall) What happens in nuclear fission?
A. Two light nuclei join to form a heavier nucleus
B. An electron is emitted from the nucleus
C. A nucleus emits only gamma radiation
D. A large nucleus absorbs a neutron and splits into two smaller nuclei, releasing neutrons and energy
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✅ D
The two or three neutrons released can go on to cause more fissions – a chain reaction. A describes fusion.
Q19 (S only, recall) What is nuclear fusion?
A. A large nucleus splitting in two
B. Two light nuclei joining to form a heavier nucleus
C. A nucleus emitting an alpha particle
D. A neutron turning into a proton
Show answer
✅ B
Some of the mass may be converted into energy. Fusion is the energy source of stars.
Q20 (S only, application) A doctor needs a radioactive tracer to inject into a patient. Which is the best choice?
A. An alpha emitter with a long half-life
B. A beta emitter with a half-life of 50 years
C. A gamma emitter with a short half-life
D. An alpha emitter with a short half-life
Show answer
✅ C
Gamma can pass out of the body to be detected and is weakly ionising. A short half-life means the patient is exposed for less time.
Examiner tip: alpha would be absorbed inside the body and is highly ionising, so it is the most dangerous choice.
Your score
Add up your marks out of 20 and multiply by 5 to get a percentage. Rough guide (not an official grade): 18–20 excellent, grade 8–9 standard | 14–17 grade 6–7 | 10–13 grade 4–5 | under 10 revise the notes and try again.
Answer key (for teachers and printing)
1 B 2 D 3 A 4 C 5 A 6 B 7 D 8 C 9 A 10 D 11 B 12 C 13 D 14 A 15 B 16 C 17 A 18 D 19 B 20 C
Revise: Atomic structure topic page | Fill the gaps: Atomic structure | Nuclear decay equations
