Q.
The masses of neutron and proton are 1.0087 and 1.0073 amu respectively- If the neutrons and protons combine to form helium nucleus of mass 4.0015 amu the binding energy of the helium nucleus will be
Mass defect, Δm^=2(mn+mp)−mHe (∵ helium nucleus has two protons and two neutrons) ∴Δm=2(1.0087+1.0073)−4.0015 =4.032−4.0015=0.0305
Binding energy, EB=Δm×931MeV =0.0305×931 =28.4MeV