What term is used to describe the ionization of a water molecule?

• A. Distillation
• B. Irradiation
• C. Radiolysis
• D. Pair production

Answer: (C)

Ionization of a water molecule caused by ionizing radiation is described as radiolysis. When radiation interacts with water, it can knock electrons off water molecules, producing ions and highly reactive radicals. This chemical decomposition of water into species such as a hydrated electron, hydroxyl radical, and hydrogen atoms drives downstream reactions that affect biological tissues and chemical systems exposed to radiation. Over time, these primary products can combine to form molecules like hydrogen gas or hydrogen peroxide, influencing dose effects and chemical changes in irradiated environments. This term is distinct from irradiation in general, which simply means exposure to radiation, and from distillation or pair production, which are unrelated processes in this context.