Answer
See explanation.
Work Step by Step
The mass defect is the total mass of the constituent particles, minus the atom’s mass.
a. Calculate the mass defect first: $6m_n+6m_H-m_C=0.09894u$.
The binding energy is $(0.09894u)\frac{931.5 MeV}{u}=92.16 MeV$
b. Binding energy per nucleon: divide the exact binding energy by 12 to obtain 7.68 MeV/nucleon.
c. This is 0.09894u/12u = 0.8245 percent of the rest mass.