What is the order of radioactive decay particles in terms of risk, from greatest to lowest?

The correct order of radioactive decay particles in terms of risk, from greatest to lowest, is indeed gamma, beta, and then alpha. This ordering is based on the penetration power and potential harm these particles can cause to biological tissues.

Alpha particles consist of two protons and two neutrons, making them relatively large and heavy. They cannot penetrate the outer layers of skin, and thus their risk is mostly present when alpha-emitting materials are ingested or inhaled. In terms of external exposure, alpha particles pose a lower risk compared to beta or gamma radiation.

Beta particles are smaller and carry a negative charge. They have a greater penetration capability than alpha particles and can penetrate skin, potentially causing damage to underlying tissues. This increases their risk level compared to alpha radiation.

Gamma rays are electromagnetic radiation with no mass or charge. They have high penetration power and can pass through the human body, causing ionization of the cells and potentially leading to significant internal damage. This makes gamma radiation the most hazardous of the three types of decay particles.

Thus, understanding the properties and interactions of these particles helps to assess their risk levels properly, confirming that alpha particles rank lowest due to their limited penetrating ability, followed by beta particles, and then gamma rays as the most dangerous