Which statement about ionizing radiation is accurate?

Which statement about ionizing radiation is accurate?

• A. It only occurs in space
• B. It travels slower than light
• C. It includes high frequency radiation such as ultraviolet and beyond
• D. It never ionizes atoms

Answer: (C)

Ionizing radiation is energy powerful enough to knock electrons off atoms. That energy depends on frequency: higher frequency means higher energy per photon. Ultraviolet light already has more energy than visible light, and X-rays and gamma rays have even more. So saying that ionizing radiation includes high-frequency radiation such as ultraviolet and beyond is accurate because these high-energy photons are capable of ionizing atoms. Not every statement is true here: ionizing radiation isn’t limited to space—Earth is constantly exposed to it from the Sun, radioactive decay, X-ray devices, and more. The idea that it always travels slower than light isn’t correct for photons, which travel at the speed of light; some ionizing particles move slower, but photons do not. And ionizing radiation by definition can ionize atoms, so saying it never ionizes is simply incorrect.

Ionizing radiation is energy powerful enough to knock electrons off atoms. That energy depends on frequency: higher frequency means higher energy per photon. Ultraviolet light already has more energy than visible light, and X-rays and gamma rays have even more. So saying that ionizing radiation includes high-frequency radiation such as ultraviolet and beyond is accurate because these high-energy photons are capable of ionizing atoms.

Not every statement is true here: ionizing radiation isn’t limited to space—Earth is constantly exposed to it from the Sun, radioactive decay, X-ray devices, and more. The idea that it always travels slower than light isn’t correct for photons, which travel at the speed of light; some ionizing particles move slower, but photons do not. And ionizing radiation by definition can ionize atoms, so saying it never ionizes is simply incorrect.