Why is it difficult to separate U 235 92 from U 238 92 ?

Isotopes can be separated only by some physical process based on atomic-mass, like diffusion. In natural uranium, the ratio of U 235 and U 238 is 1 : 145 , and the ratio of their atomic masses is very close to 1 . So, the difference in their atomic masses is very close to 1 and correspondingly the difference in the root-mean-square values of velocities of the atoms of these isotopes is very small v 1 r m s v 2 r m s = m 2 m 1 . Hence, to separate them, some gaseous compound of uranium U F 6 is taken, and it has to be diffused thousands of times in ultracentrifuges in series to get the required concentration of U 235

Complete the equation: U 235 92 + n 1 0 → . . . .

U 235 92 + n 1 0 → U 236 92 → B 56 a 141 + K 36 r 92 + 3 n 1 0 + energy This is the nuclear fission reaction induced by a neutron. The energy released in the process is of the order of 200 MeV per fissioning nucleus. The disintegration energy appears as the kinetic energy of fragments and neutrons.