SOLUTION

U₂₃₅ will undergo fission by either fast or slow neutrons.

When a nucleus of uranium-235 undergoes fission, it splits into two smaller atoms and, at the same time, releases neutrons ( n) and energy. Some of these neutrons are absorbed by other atoms of uranium-235. In turn, these atoms split apart, releasing more energy and more neutrons.

A crucial difference between U-235 and U-238 is that a nucleus of U-235 will undergo fission when any neutron, even one moving very slowly, collides with it.