Final answer:
When uranium is bombarded with neutrons, it undergoes fission, the particle X in the fission reaction of uranium is a) Neutron.
Step-by-step explanation:
The particle X in the fission reaction of uranium is a neutron. When uranium-235 is bombarded with a neutron, it absorbs the neutron and forms an unstable uranium-236 nucleus. The uranium-236 then rapidly breaks apart into two smaller nuclei, barium-141 and krypton-92, along with several neutrons, and releases a large amount of energy.
This fission reaction follows the general equation: 235U + n → 141Ba + 92Kr + n + energy. Neutrons are essential in the process of nuclear fission as they help sustain and propagate the chain reaction. They are responsible for initiating the fission of additional uranium-235 nuclei, which releases more neutrons and energy. So therefore the correct answer is a) Neutron.