Radiation Safety Practice Exam

Which statement is true about alpha particles?

1. They are negatively charged.

2. They have two neutrons.

3. Their mass is similar to that of electrons.

4. They travel much slower than gamma rays.

The correct answer is: They have two neutrons.

The statement indicating that alpha particles have two neutrons is accurate. Alpha particles are composed of two protons and two neutrons; thus, they are essentially helium nuclei. This composition is important because it determines the particle's behavior in interactions with matter and its overall range and penetrating power. The charge of an alpha particle is positive due to the presence of the two protons, which is why saying they are negatively charged is incorrect. Additionally, while alpha particles are significantly heavier than electrons, with a mass approximately 4 times that of a hydrogen atom, stating that their mass is similar to that of electrons does not hold true. Alpha particles are among the heavier forms of radiation, which impacts their movement through materials. Lastly, regarding speed, alpha particles are indeed much slower than gamma rays; however, the specific statement regarding their neutron composition best describes their identity. Understanding these characteristics helps clarify the unique properties of alpha radiation in the context of radiation safety.