Energy emitted from a radioactive atom in the form of a ray or particle that can ionize an atom is called:

The correct answer is ionizing radiation. This term specifically refers to energy emitted from radioactive atoms in the form of particles or electromagnetic waves that have enough energy to remove tightly bound electrons from atoms, thus creating ions. This characteristic of ionizing radiation makes it particularly relevant in various fields, including medicine and nuclear energy, where the ability to ionize atoms can lead to chemical changes and biological effects.

Radioactive contamination refers to the unwanted presence of radioactive materials on surfaces or within solids, liquids, or gases, which is a different concept that does not describe the energy or particles emitted. Radioactive material pertains to substances that contain unstable atomic nuclei that release energy in the form of radiation but again does not define the emitted rays or particles themselves. Lastly, radioactivity is the general term for the process by which unstable atomic nuclei lose energy by emitting radiation. While it encompasses the concept of ionizing radiation, it does not specifically denote the energy emissive aspect associated with ionization. Thus, ionizing radiation is the most precise term for the energy emitted that can ionize other atoms.