GCSE Physics Radioactivity questions by topic

Complete the table about the three nuclear radiations.

1. (a)Nature of alpha.[1]
2. (b)Beta absorber.[1]
3. (c)Nature of gamma.[1]
4. (d)Gamma absorber.[1]
5. (e)Which radiation is the least ionising?[1]

A source has an activity of 640 Bq and a half-life of 2 days.

1. (a)State the activity after 2 days.[1]
2. (b)State the activity after 4 days.[1]
3. (c)Calculate how many half-lives have passed after 8 days.[1]
4. (d)State the activity after 8 days.[1]

Define irradiation and contamination, and state which one washing with water can reduce.

1. (a)Define irradiation.[1]
2. (b)Define contamination.[2]
3. (c)Which one can washing reduce?[1]

Name one natural and one man-made source of background radiation, and explain why measurements must be corrected for it.

1. (a)One natural source.[1]
2. (b)One man-made source.[1]
3. (c)Explain the correction.[2]

A Geiger–Müller tube records a source’s count rate over a week. The background rate is 12 s⁻¹.

1. (a)Calculate the corrected rate for each reading.[2]
2. (b)Determine the half-life.[2]
3. (c)Predict the corrected rate after 10 days.[2]
4. (d)State why the rate never quite reaches zero.[1]

Complete these nuclear equations by giving the missing values.

1. (a)²¹⁰₈₄Po → ? + ⁴₂α (give A and Z of the daughter).[2]
2. (b)¹⁴₆C → ¹⁴₇N + ? (name the emitted particle).[2]
3. (c)Explain why gamma emission changes neither A nor Z.[2]

A hospital chooses between two isotopes for a tracer: isotope P (beta emitter, half-life 30 years) and isotope Q (gamma emitter, half-life 6 hours).

1. (a)State which isotope should be used and why its radiation suits detection.[2]
2. (b)Explain why its half-life suits the patient.[2]
3. (c)Give one property of the radiation that makes the other isotope unsuitable.[2]

Explain why alpha sources are more dangerous inside the body than outside it, and why gamma sources are the reverse.

1. (a)Explain the inside-body danger of alpha.[3]
2. (b)Explain the external danger of gamma and why alpha barely matters outside.[3]

A sample of a medical isotope has activity 900 Bq at 08:00 and a half-life of 8 hours.

1. (a)Calculate the activity at 16:00 the same day.[2]
2. (b)Calculate the activity at 08:00 the next day.[2]
3. (c)Determine after how many hours the activity first falls below 30 Bq.[3]

A technician claims: “This source has decayed for three half-lives, so three quarters of it has gone and it is now safe to handle without precautions.”

1. (a)Verify the fraction that has decayed.[2]
2. (b)Explain the two errors in calling the source “safe”.[4]
3. (c)State what determines when a source can be handled safely.[1]

Evaluate the use of americium-241 (an alpha emitter with a half-life of 432 years) in household smoke alarms.

1. (a)Explain how the alarm detects smoke.[3]
2. (b)Explain why an alpha emitter suits this use.[2]
3. (c)Give one risk and explain why it is considered acceptable.[3]

An archaeologist has two dating methods: carbon-14 (half-life 5 700 years) and a sodium isotope (half-life 15 hours).

1. (a)State which isotope suits dating ancient wood and why.[2]
2. (b)Explain why the sodium isotope cannot date wood at all.[2]
3. (c)State one limitation of carbon-14 dating for very old samples.[2]