The masses of neutron and proton are `1.0087` a.m.u. and `1.0073` a.m.u. respectively. If the neutrons and protons combine to form a helium nucleus (alpha particle) of mass `4.0015`a.m.u. The binding energy of the helium nucleus will be `(1 a.m.u. = 931 MeV)`.

Options

A. 14.2 MeV
B. 28.4 MeV
C. 20.8 MeV
D. 27.3 MeV

Answer

B

Explanation

Mass defect `Deltam = [2m_P + 2m_N - " mass of helium nucleus " ]`
`=2xx [ 1.0087 + 1.0073 0 - 4.0015`
= 0.0305 amu.
The energy equivalent of 1amu = 931 MeV
`therefore` Binding energy = Energy equivalent of mass defect
`because B.E = 931xx0.0305 = 28.4 MeV`