A uranium-235 atom is moving forwards in a reactor with a velocity of 6.2 x 105 ms-1 when it undergoes spontaneous fission into a krypton (Kr) atom and a Barium (Ba) atom. The Kr atom is ejected backwards at a velocity of 3.3 x 106 ms-1 whilst the Ba atom is projected forwards (atomic masses are: U = 235 u, Kr = 95 u and Ba = 140 u) The velocity of the barium atom after fission has occurred is about: A. 1.9 x 105 ms-1 B. 8.7 x 106 ms-1 C. 3.3 x 106 ms-1 D. 2.6 x 106 ms-1