What is the difference between X-rays and gamma rays?

• A. No functional difference; X-ray origin = electron acceleration; gamma origin = radioactive decay
• B. X-rays are emitted during radioactive decay; gamma rays from electron acceleration
• C. X-rays have charge; gamma rays are massless
• D. X-rays are slower than gamma rays

Answer: (A)

X-rays and gamma rays are both photons—the same kind of electromagnetic radiation. The difference you’re tested on is about how they’re produced, not what they fundamentally are. X-rays come from electron-related processes (such as electrons changing energy levels or being decelerated), while gamma rays come from nuclear processes (like radioactive decay or nuclear transitions). Because of this origin distinction, the statement that there is no functional difference and that X-rays are from electron acceleration while gamma rays come from radioactive decay matches the common convention used in practice.

The other options mix up the facts: photons have no charge and no rest mass, and they travel at the speed of light in vacuum, so saying X-rays are slower or that gamma rays carry charge or mass doesn’t fit. Also, while X-rays can be produced in various ways, gamma rays are not defined by electron acceleration.