[填空题]
Instead of giving atomic masses for nu u-r9eoyx ,y/p/mk q3bclides as in Appendix B, some:2 9cia.lazf h Tables give the mass excei af9lc:.2h azss, $\Delta$, defined as $\Delta = M - A$, where $A$ is the mass number and $M$ is the mass in u. Determine the mass excess, in u and in $\text{MeV}/c^2$, for:
(a) $_{2}^{4}\text{He}$; $\ \text{u}$ $\ \text{MeV}/c^2$
(b) $_{6}^{12}\text{C}$;
(c) $_{47}^{107}\text{Ag}$; $\ \text{u}$ $\ \text{MeV}/c^2$
(d) $_{92}^{235}\text{U}$; $\ \text{u}$ $\ \text{MeV}/c^2$
(e) From a glance at Appendix B, can you make a generalization about the sign of $\Delta$ as a function of $Z$ or $A$?
