The mass excess of a nucleus is defined as the difference between the atomic mass (in atomic mass units, u), and the mass number of the nucleus, A. Using the mass-energy conversion 1 u = 931.49 MeV/c2, this mass excess is usually expressed in kilo-electron-volts (keV). The table below presents the mass excess for several nuclei (from the Berkeley National Lab NuBase database):

(a) Calculate the atomic mass (in atomic mass units) for each of the nuclei in the table. For reference, the atomic mass of the neutron is given.
(b) Using your results from part (a), determine the mass-energy difference between the initial and final states for the following possible fission reactions:

(c) Will these reactions occur spontaneously?

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No. Nucleus Mass Mass excess, AmAtomic mass (u) number, A (keVc) 1.00866491 8,071.3 76,034 85,496 83,27 72,990 -86,336 67,250 gn 252 256 140 140 112 109 98 256 Fm Ba Xe Pd 00 140 140 54 40 140 109 RT 98 100