The element that is marked X in the fission is 95/36Kr
What is nuclear fission?
A nuclear reaction known as nuclear fission occurs when an atom's nucleus breaks into two or more smaller nuclei while releasing a sizable quantity of energy. Usually, a neutron bombardment of the nucleus initiates this process. Additionally, nuclear fission plays a crucial role in nuclear weapons.
In the fission of the Uranium, the nuclide is bombarded with neutrons and then we have the creation of a barium and the krypton nuclides alongside more neutrons.