Question- Lanthanum-139 is a stable nuclide but lanthanum-140 is unstable (t1/2 = 40 hr). What rule of thumb involving nuclear stability is involved?
Select all that apply.
Lanthanum-139 is stable because it has a magic number of neutrons (82).
Lanthanum-139 is stable because it has an odd number of protons and an even number of neutrons (the "odd-even rule").
Lanthanum-140 is unstable because it has a magic number of neutrons (83).
Lanthanum-140 is unstable because it has an odd number of protons and an odd number of neutrons (the "odd-even rule").
None of these.