The atomic number for Pb is 82 ∴ Pb has 82 protons and 206-82 = 14 protons The actual mass of Pb nuclei is =(82 × mass of the proton) + (124 × mass of neutron) =(82× 1.00728) + (124 × 1.008664) amu = 207.6713 amu The mass of lead which is given is 205.9744 amu ∴mass defect is m = 207.6713 - 205.9744 = 1.6969 amu =1.6969 × 1.66054 × 10⁻²⁷kg =2.818 × 10⁻²⁷kg The binding energy is E = mc² C is the speed of light in vacuum = 2.9979 × 10⁸m/s ∴ E = 2.532 × 10×⁻¹⁰ J/mol = 2.532 × 10⁻¹⁰ × 6.023 × 10²³ J/mol = 1.53811 × 10¹⁴ J/mol
