Atoms contain subatomic particles called protons and neutrons. when these protons and neutrons split, a lot of energy is released what kind of energy is this?

Which statement is the best definition of an atom? a) anything that has mass and occupies space. b) the smallest particle that has the properties of an element. c) a substance that cannot be broken down chemically into simpler substances. eliminate d) the smallest unit of a substance that exhibits all of the properties characteristic of that substance.