What is produced when the nucleus splits during fission?

When a nucleus splits during fission, the process results in the formation of two smaller nuclei, known as fission fragments, along with the release of several neutrons. This occurs when a heavy nucleus absorbs a neutron and becomes unstable, leading it to break apart. The fission process not only produces these two smaller nuclei but also releases energy in the form of kinetic energy from the fragments and the kinetic energy of the emitted neutrons.

The emitted neutrons are significant because they can induce further fission in nearby nuclei, potentially leading to a chain reaction. The fission fragments are usually isotopes of smaller elements and can be in an excited state, emitting additional energy as they stabilize.

In contrast, one subatomic particle, three stable particles, or a higher atomic mass nucleus do not accurately describe the outcome of the fission process, as they do not account for the actual splitting of the nucleus and the release of neutrons. Thus, the accurate representation of the fission process is the production of two smaller nuclei and several neutrons.