What term describes the mass converted into energy during a nuclear reaction?

The mass converted into energy during a nuclear reaction is best described by the term "mass-energy equivalence." This principle is fundamentally rooted in Einstein's famous equation, E=mc², which states that energy (E) is equal to mass (m) multiplied by the speed of light (c) squared. In the context of nuclear reactions, small amounts of mass are transformed into significant amounts of energy, highlighting the direct relationship between mass and energy.

This concept is especially vital in understanding nuclear fission and fusion, where changes in the mass of the nucleus result in the release of large amounts of energy. The mass-energy equivalence principle not only explains how energy is released in these processes but also underscores the conservation of energy and mass in physics.

Other terms like energy-mass equivalence or energy theorem do not accurately capture the direct relationship implied by Einstein's concept of mass-energy equivalence, while the nuclear energy ratio is not a standard term used in this context. Hence, mass-energy equivalence is the precise terminology used to describe the mass that transforms into energy during nuclear reactions.