The energy required to separate the typical middle mass nucleus `._(50)^(120)Sn` into its constituent nucleons ( Mass of `._(50)^(120)sn=119.902199u`, mass of proton `=1.007825 u` and mass of neutron `=1.008665 u`)

Explanation

(a) Number of neutrons =120-50=70
The mass defect `Deltam=Z.(m_H)+N(m_n)=M_(Sn)`
`=50xx1.007825 u +70 xx 1.008665 u-119.902199 u`
(Taking atomic masses , the of electrons are cancelled out )
=120.99780 u -199.902199 u
`= 1.095601 u = 1.096 u`
`therefore` The required energy `E=Deltam.c^2=(1.096u) xx(931.5 MeV//u)`
=1021 MeV
This is called the binding for this nuclide .
(b) B.E per nucleon `=E/A=(1021MeV)/(120)=8.51` MeV/ nucleon