Which of the following is an example of ionizing radiation?

Ionizing radiation is defined as radiation that carries enough energy to liberate electrons from atoms or molecules, thereby creating ions. X-rays fall into this category because they possess high energy levels capable of penetrating matter and displacing electrons from their orbits. This ability to ionize atoms is critical in various applications, including medical imaging and cancer treatment, but it also means that exposure must be managed carefully due to potential biological effects.

In contrast, the other types of radiation mentioned—microwaves, visible light, and radio waves—are forms of non-ionizing radiation. They do not have sufficient energy to ionize atoms, which typically limits their safety concerns and effects on biological tissues compared to ionizing radiation like X-rays. Hence, X-rays are a prime example of ionizing radiation due to their energy and impact.