Let us first find the B.E. of each copper nucleus and then we can find binding energy of 300 g of $\,{}^{\underset{29}{63}}$ Cu Mass of 29 protons = 29 × 1.00783 = 29.22707 u Mass of 34 neutrons = 34 × 1.00867 = 34.29478 u Total theoretical mass = 63.52185 u Actual mass of Cu nucleus = 62.92960 u Mass of defect = Theoretical mass – Actual mass = 0.59225 u B.E. of each Cu nucleus = Δm [931.5 MeV] = 0.59225 [931.5 MeV] = 551.385 MeV Number of atoms in 3 g of copper n = $\frac{\text{Avagadro number}}{\text{Mass Number}}$ × 3 or n = $\frac{6.023 \times 10^{23} \times 3}{3}$ = 2.8 × $10^{22}$ Total binding energy in 3 g of copper = 2.86 × $10^{22}$ × 551.385 MeV = 1.6 × $10^{25}$ MeV So, the energy required to separate all the neutrons and protons from each other in 3 g copper coin will be 1.6 × $10^{25}$ MeV.