Q: Find the binding energy of (_{26}Fe^{56}) Atomic mass of Fe is 55.9349 u and that of hydrogen is 1.00783 u and

mass of neutron is 1.00876 u.

Sol: Mass of he hydrogen atom m_{H} = 1.00783 u;

Mass of neutron m_{n} = 1.00867 u;

Atomic number of iron , Z = 26; mass number of iron A = 56 ;

Mass of iron atom M_{a} = 55.9349 u

Mass defect , Δm = [Z m_{H} + (A-Z) m_{n} ] – M_{a}

= [26 x 1.00783 +(56-20)1.00867]-55.93493 u = 0.5287 u.

Binding energy = (Δm)c^{2} = (0.5287)(931.5 MeV) MeV

= 492.55 MeV.