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Leaving Cert Physics & Chemistry: Radioactivity

How often Radioactivity comes up on the Physics & Chemistry papers, every year it was asked, and questions to try.

HL Asked on 9 of the last 9 Higher Level papers, most recently in 2025. banker

OL Asked on 9 of the last 9 Ordinary Level papers, most recently in 2025. banker

Radioactivity, Higher Level(7 marks)

Quick ones on Radioactivity.

(a)An alpha particle consists of…
  1. A fast-moving electron
  2. 2 protons and 2 neutrons
  3. A high-energy photon
(b)An isotope has a half-life of 5 days. Mass of an 80 g sample still undecayed after 15 days?
  1. 40 g
  2. 20 g
  3. 10 g
(c)Which radiation needs thick lead or concrete to absorb most of it?
  1. Gamma
  2. Beta
  3. Alpha
Show the answers

(a) 2 protons and 2 neutrons

(b) 10 g

(c) Gamma

Your turn: Higher Level questions on Radioactivity.

Higher Level

Asked on 9 of the last 9 Higher Level papers, most recently in 2025. banker

Every paper, year by year

YearWhere it came up
2025Q1(q), Q6(a)
2024Q6(d)
2023Q1(q), Q1(r)
2022Q6(d)
2021Q1(q), Q1(r)
2019Q1(n), Q1(o)
2018Q1(o), Q6(d)
2017Q6(c)
2016Q1(n), Q6(d)

Links open the State Examinations Commission’s paper for that year.

More Radioactivity questions

Radioactivity, 2 marks

Which is a medical use of radioactivity?

  1. Setting broken bones with alpha radiation
  2. Measuring blood pressure with beta radiation
  3. Killing cancer cells with gamma radiation
Show the answer

Killing cancer cells with gamma radiation

Gamma rays from a source such as cobalt-60 are aimed at a tumour to destroy cancer cells (radiotherapy). Radioisotopes are also used as tracers.

Radioactivity, 2 marks

Which radiation is not deflected by an electric or a magnetic field?

  1. Beta
  2. Gamma
  3. Alpha
Show the answer

Gamma

Gamma rays are electromagnetic waves with no charge, so fields do not deflect them. Alpha (+) and beta (−) are charged and bend in opposite directions.

Ordinary Level

Asked on 9 of the last 9 Ordinary Level papers, most recently in 2025. banker

Every paper, year by year

YearWhere it came up
2025Q6(d)
2024Q1(q), Q6(d)
2023Q1(q), Q6(c)
2022Q1(p), Q1(q), Q6(b)
2021Q1(q), Q6(b)
2019Q6(b)
2018Q1(n), Q6(b)
2017Q1(n), Q1(o), Q6(b)
2016Q1(o), Q6(b)

Links open the State Examinations Commission’s paper for that year.

More Radioactivity questions

Radioactivity, 2 marks

Radioactivity is?

  1. Emission of electrons from a metal surface when light shines on it
  2. Splitting of a large nucleus when it is hit by a neutron
  3. Unstable nuclei breaking up by themselves, giving radiation
Show the answer

Unstable nuclei breaking up by themselves, giving radiation

It happens by itself (spontaneously) and cannot be sped up or slowed by heat or pressure. The radiation can be alpha, beta or gamma.

Radioactivity, 2 marks

An alpha particle consists of?

  1. 2 protons and 2 electrons
  2. 2 protons and 2 neutrons
  3. A single electron
Show the answer

2 protons and 2 neutrons

An alpha particle is a helium nucleus, charge +2. A beta particle is a fast electron from the nucleus; gamma is an electromagnetic wave.

Radioactivity, 2 marks

Which radiation is the most penetrating?

  1. Gamma
  2. Alpha
  3. Beta
Show the answer

Gamma

Gamma needs thick lead or concrete to stop it. Beta is stopped by a few mm of aluminium, alpha by paper. The order for ionising power is the reverse.

Other Physics & Chemistry topics

All of Leaving Cert Physics & Chemistry