The binding energy of helium 4//2He is?

[atomic mass of proton = 1.00783U,
atomic mass of neutron = 1.00867U]

A. 4.033U
B. 2.017U
C. 0.033U
D. 0.330U

Correct Answer: Option C
Explanation
The binding energy of a nucleus is the work done or energy needed to separate completely the nucleons (protons and neutrons) apart. Again, experiment shows that the total mass of all individual nucleons is greater than that of the nucleus, in which they are together. This difference in the mass is the measure of the binding energy of the particular nucleus.

it has altogether 4 nucleons 2 protons and 2 neutrons
2:H = 2 x 1.00783 = 2.01566
2:n = 2 x 1.00867 = 2.01734
∴ 2:H + 2:n = 4.03300u
But the helium nucleus has a mass of 4.00260u
∴ Binding energy = difference of nucleons and nucleus
= 4.03300U – 4.00260U = 0.03040U