Radiation energy is energy emitted or transmitted from a source in the form of particles and waves. It determines whether radiation is ionizing or non-ionizing.

• A. Energy that travels only as waves.
• B. Energy emitted from a source as particles or waves; determines ionizing or non-ionizing.
• C. Energy stored in chemical bonds.
• D. Energy that has no interaction with matter.

Answer: (B)

Radiation energy is the energy carried away from a source as either particles or electromagnetic waves, and what makes it ionizing or non-ionizing is the energy per quantum it delivers. Each quantum—whether a photon or a particle—has a specific energy related to the wave’s frequency or the particle’s nature. If that energy is enough to overcome the binding energy of electrons in atoms, it can eject electrons and create ions and radicals, which is what defines ionizing radiation. High-energy photons in the ultraviolet, X-ray, and gamma-ray ranges have this capability, while lower-energy radiation such as visible light and below generally does not ionize (though it can heat tissue). The statement captures both modes of energy transport and the link to ionization; other descriptions are incomplete or inaccurate because they ignore particle radiation, confuse radiation with chemical energy, or imply no interaction with matter at all.