20 neutrons and 20 protons (with electrons) separately would have a mass of 40.328 amu
As a Ca atom with electrons, the mass is 39.975 amu
The mass difference (binding energy) of 0.353 amu (after converting to kg) can be converted to Joules using
E = m c^2, OR
if you want it in Mev, just multiply by 931 Mev/amu
Q.4. Calculate the binding energy per nucleon of 20 Ca40 which has atomic mass of 39.975 a.m.u The mass of
hydrogen atom is 1.0078 a.m.u and that of neutron is 1.0086 a.m.u (1 a.m.u = 931 Mev) (10)
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