Radiation Safety Practice Exam

Which particle is defined as a fast-moving electron released by a nucleus during radioactive decay?

1. Alpha particle

2. Beta particle

3. Gamma ray

4. Neutron

The correct answer is: Beta particle

The particle defined as a fast-moving electron released by a nucleus during radioactive decay is the beta particle. Beta decay is a type of radioactive decay in which a neutron in the nucleus transforms into a proton while releasing an electron (the beta particle) and an antineutrino. This process increases the atomic number of the element while leaving its mass number unchanged, effectively transforming the original element into another element. In contrast, an alpha particle consists of two protons and two neutrons and is emitted during a different type of decay known as alpha decay. Gamma rays are electromagnetic radiation released with no mass or charge, commonly emitted alongside other forms of decay but not as a particle. Neutrons are neutral particles found within the nucleus that can also be released during certain types of nuclear reactions, but they do not represent a fast-moving electron. Therefore, understanding these distinctions highlights why the beta particle is the correct response to the question.