Radioactivity

In which applications are gamma-rays used?

May/June 2016

Fig. 11.1 shows a nuclear fusion reaction. At an extremely high temperature, the nuclei of the two isotopes $^{2}_{1}\text{H}$ and $^{3}_{1}\text{H}$ join together. Energy is released and two new particles are produced, particle A and particle B.

May/June 2016

A source of background radiation is cosmic rays. Cosmic rays that enter the Earth’s atmosphere are called primary cosmic rays. Most of these rays are fast-moving protons or fast-moving alpha-particles. The Earth’s magnetic field together with the Earth’s atmosphere reduces how many primary cosmic rays reach the Earth’s surface.

May/June 2017

A smoke detector holds a tiny radioactive source of americium-241. This source gives out alpha-particles.

May/June 2018

A teacher performs a radioactivity experiment with the apparatus shown in Fig. 11.1. Count rate is found by measuring the count in one minute.

May/June 2019

Stars form within a cloud of gas and dust in space. As a star begins to form, the cloud shrinks as it collapses.

May/June 2019

Table 10.1 gives information about the type and some properties of alpha, beta and gamma emissions. Fig. 10.1 shows surgical instruments sealed inside plastic bags, with the bags placed in thin plastic boxes. A conveyor belt carries the boxes near to a cobalt-60 source, which sterilises the instruments. The cobalt-60 source is a radioactive isotope of cobalt that gives out gamma-radiation. Fig. 10.2 shows an alpha-particle moving close to the nucleus of a gold atom.

May/June 2021

A detector is positioned a few centimetres from a very radioactive source that emits beta-particles, as illustrated in Fig. 11.1.

May/June 2021

Table 9.1 gives the details of seven different nuclides.

May/June 2022

Thorium-229 is a radioactive isotope that is used in several medical applications involving alpha-particles and beta-particles.

May/June 2022

Which radioactive isotope can be used to detect cracks or flaws in metal components?

May/June 2023

Carbon-14 is one isotope of carbon, and its radioactive decay has a half-life of 6000 years.

May/June 2023

A radioactive source gives out $\alpha$-particles, $\beta$-particles and $\gamma$-radiation.

May/June 2023

Table 7.1 presents four separate nuclei.

May/June 2024

Alpha particles may be released from the nuclei of radioactive elements. This emission happens at random and is spontaneous.

May/June 2024

Plutonium-239 ($^{239}_{94}\text{Pu}$) is an isotope that serves as fuel in some nuclear reactors.

May/June 2025

Lead has proton number (atomic number) 82. The radioactive isotope lead-209 ($^{209}_{82}\text{Pb}$) decays by emitting beta-particles.

Oct/Nov 2015

Sodium-24 and sodium-23 are two isotopes of sodium. During decay, sodium-24 is radioactive and gives out beta-particles together with gamma-rays.

Oct/Nov 2016

Plutonium-238 is a radioactive isotope that undergoes decay by emitting alpha-particles. It also gives off gamma-rays.

Oct/Nov 2016

A sample of the radioactive isotope radon-222 undergoes decay by emitting alpha-particles.

Oct/Nov 2017

Two neutral atoms are atoms of the same element but with different isotopic forms.

Oct/Nov 2018

In Fig. 6.1, a radiation detector is sitting on a laboratory bench. The detector is turned on, six count-rate readings are taken, and a sample of the radioactive isotope cobalt-60 is positioned close to the detector.

Oct/Nov 2018

Phosphorus-32 ($^{32}_{15}\text{P}$) is a phosphorus isotope that undergoes radioactive decay.

Oct/Nov 2020

Technetium-99m is a radioactive isotope that is used in medical scanning. It is introduced into the body by injection, and its emissions are detected from outside the body. Which characteristics of technetium-99m make it suitable for use in medical scanning?

Oct/Nov 2021

The isotope yttrium-90 ($^{90}_{39}\text{Y}$) undergoes radioactivity. It emits a beta particle and decays to form Q. Product Q is stable.

Oct/Nov 2021

Isotope X is radioactive and undergoes alpha-particle emission to form a stable isotope.

Oct/Nov 2021

Protactinium-234 ($^{234}_{91}\text{Pa}$) is one radioactive isotope of protactinium, and it decays into uranium-234 ($^{234}_{92}\text{U}$).

Oct/Nov 2022

A radioactive isotope is introduced into a patient during a medical examination. The radiation it gives off is picked up from outside the body. What suitable properties should this isotope have?

Oct/Nov 2024

The nuclide symbol for radioactive hydrogen-3 is $^{3}_{1}\text{H}$.

Oct/Nov 2024

The isotope thorium-230 ($^{230}_{90}\text{Th}$) undergoes decay by emitting an alpha particle ($\alpha$-particle).

Oct/Nov 2024

A smoke alarm includes a radioactive source, S. The radiation from S that is useful is stopped by only a few centimetres of air. What type of useful radioactive radiation is emitted by S?

Oct/Nov 2025

Which nuclide results when thorium-223, $^{{223}}_{{90}}\mathrm{Th}$, emits an alpha-particle?

Oct/Nov 2025

A radioactive source is positioned $2.0\text{ cm}$ from a Geiger-Müller (G.M.) tube linked to a counter. A sheet of paper is inserted between the source and the G.M. tube. The counter reading falls, but it remains above the background radiation count rate. The paper is then replaced with a sheet of aluminium, and the count rate falls to the background radiation count rate. What radiation is emitted by the source?

Oct/Nov 2025

The nuclide symbol for the radioactive isotope radon-222 is $^{222}_{86}\mathrm{Rn}$. A radon-222 atom decays by releasing an alpha particle (α-particle). Radon-222 is used in an alpha-particle scattering experiment. Fig. 8.1 shows a beam of alpha particles from radon-222 striking a very thin gold sheet in a vacuum. Diagram labels: radon-222, beam of alpha particles, thin gold sheet, vacuum, position J, position K.

Oct/Nov 2025