The binding energy of helium - 4 is 28 MeV. a. What is the mass of a helium nucleus (round to 5 decimal places) ?

4.001805 amu

Explanation:

931 Mev = 1 amu

28 Mev = 28 / 931 Mev

=.030075 amu

Helium nucleus consists of 2 proton and 2 neutron.

Binding energy in terms of amu

= total mass of 2 neutron and 2 proton - mass of nucleus of helium

mass of nucleus of helium = total mass of 2 neutron and 2 proton - Binding energy in terms of amu

mass of 2 neutron = 2 x 1.008664 = 2.017328

mass of 2 proton = 2 x 1.007276 = 2.014552

total = 4.03188

So mass of helium nucleus = 4.03188 -.030075

= 4.001805 amu.