U-235 and Pu-239 are examples of which category?

U-235 and Pu-239 are examples of which category?

• A. Common fissionable fuels
• B. Nuclear Fertile Elements
• C. Naturally occurring
• D. Half-life

Answer: (A)

The main idea is identifying materials that can sustain a chain reaction. U-235 and Pu-239 are fissile fuels—they fission readily when hit by neutrons and release additional neutrons that keep the reaction going, along with energy. That makes them classic examples of common fissionable fuels used in reactors and weapons. They’re not fertile materials (which can be turned into fissile materials, like U-238 becoming Pu-239, or Th-232 becoming U-233), and Pu-239 isn’t naturally abundant, while U-235 occurs only in small amounts naturally; so labeling them as naturally occurring isn’t accurate for the category as a whole. The concept of half-life doesn’t describe them as a group.

The main idea is identifying materials that can sustain a chain reaction. U-235 and Pu-239 are fissile fuels—they fission readily when hit by neutrons and release additional neutrons that keep the reaction going, along with energy. That makes them classic examples of common fissionable fuels used in reactors and weapons. They’re not fertile materials (which can be turned into fissile materials, like U-238 becoming Pu-239, or Th-232 becoming U-233), and Pu-239 isn’t naturally abundant, while U-235 occurs only in small amounts naturally; so labeling them as naturally occurring isn’t accurate for the category as a whole. The concept of half-life doesn’t describe them as a group.