"Heavy particles that travel only a few centimeters in the air" best describes which type of ionizing radiation?

Heavy particles that travel only a few centimeters in the air are best described as alpha particles. These particles consist of two protons and two neutrons, making them significantly heavier than other forms of radiation, such as beta particles or gamma rays. Due to their mass and charge, alpha particles interact strongly with matter; as a result, they have a limited range and can only travel a short distance in the air, typically just a few centimeters.

In laboratory settings, understanding the characteristics of different types of ionizing radiation is crucial for ensuring the safety of personnel and animals. Alpha particles are less penetrating than beta particles, which are lighter and can travel further. Similarly, gamma rays and X-rays are forms of electromagnetic radiation that can penetrate much deeper into materials, including human tissue, and thus can travel considerably farther in the air. Therefore, the defining traits of alpha particles align perfectly with the given description.