The mass defect refers to the amount of mass that has been converted to energy to hold the nucleus together. That means the mass defect is what you're using in your equation to calculate E.
E=mc2E=(5.0531×10−29)(3×108)2E=4.55×10−12
The binding energy is 4.55 x 10^(-12) J.
Let me know if you have any questions!
