Answer:
1720 MeV
Explanation:
Thorium has 90 protons and 142 neutrons
The mass of each proton is 1.007277 amu
The mass of each neutron is 1.008665 amu
The mass of 90 protons is 90 * 1.007277 amu = 90.65493 amu
The mass of 142 neutrons is 142 * 1.008665 amu = 143.23043 amu
Total calculated mass of nucleons = 90.65493 amu + 143.23043 amu = 233.88536
Mass defect = 233.88536 amu - 232.038 amu = 1.84736 amu
We convert from amu to MeV using the conversion factor of 931
Binding energy = 1.84736 amu * 931 = 1720 MeV
