Locate the nuclides displayed in Table 42-1 on the nuclidic chart of Fig. 42-5. Verify that they lie in the stability zone.

Table 42-1 on the nuclidic chart of Figure 42-5 is given.

A nuclidic chart is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons and the other represents the number of protons in the atomic nucleus. Each box represents a particular nuclide and is color-coded according to its predominant decay mode. The stability zone of the nuclides lies in the upper valley of the belt region.

Locate a nuclide from Table 42-1 by finding the coordinate (N,Z) of the corresponding point in Fig. 42-4. It is clear that all the nuclides listed in Table 42-1 are stable except the last two, ${}^{227}\mathrm{Ac}\mathrm{and}{}^{239}\mathrm{Pu}$.

Hence, all the nuclides lie in the stability zone except two nuclides ${}^{227}\mathrm{Ac}\mathrm{and}{}^{239}\mathrm{Pu}$.