Neutron absorption can lead to which outcome?

• A. They are absorbed and sometimes produce radioactive atoms
• B. They annihilate with electrons
• C. They vanish in a vacuum
• D. They are repelled by hydrogen

Answer: (A)

Neutron absorption means a nucleus captures a neutron and becomes a heavier isotope. This entry of a neutron often leaves the nucleus in an excited state and it typically relaxes by emitting radiation or may undergo beta decay to a different, sometimes radioactive, nucleus. So absorption can lead to radioactive atoms, which is why this outcome is the best fit. The other ideas don’t match how neutrons interact: annihilation with electrons would require antimatter (positrons do this with electrons, not neutrons); neutrons don’t just vanish in a vacuum—they would continue traveling until they react or decay; and they aren’t repelled by hydrogen—neutrons interact with hydrogen and can be slowed, scattered, or captured, not repelled.