Instead of giving atomic masses for nuclides as in Appendix B, some Tables give the mass excess,

Question:

Instead of giving atomic masses for nuclides as in Appendix B, some Tables give the mass excess, ∆, defined as ∆ = M - A, where A is the atomic mass number and M is the mass in u. Determine the mass excess, in u and in MeV/c2, for:
(a) 42He;
(b) 126C;
(c) 8638Sr;
(d) 23592U;
(e) From a glance at Appendix B, can you make a generalization about the sign of ∆ as a function of Z or A?