Nuclear & particle physics

The half-life of a radioactive isotope is the time required for half of the unstable nuclei in a sample to decay, which directly halves its activity. Option B is incorrect because radioactive decay reduces the mass of the parent isotope rather than doubling it. Option D is incorrect because half-lives vary widely between different isotopes, from fractions of a second to billions of years.

Alpha particles consist of two protons and two neutrons, which is identical to a helium-4 nucleus. This composition gives them a double positive charge and a relatively large mass. Option A describes beta-minus particles, while Option C describes gamma radiation, which consists of high-energy photons rather than massive particles.

Alpha particles consist of two protons and two neutrons, which is identical to a helium-4 nucleus. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Option B is incorrect because radioactive decay reduces the mass of the parent isotope rather than doubling it.

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