Natural germanium has only one radioactive isotope - germanium 76.
27 artificial radioisotopes of germanium are known.
Germanium has 9 isotopes.
Germanium has 5 naturally occurring stable isotopes: 70, 72, 73, 74, 76. Dozens of other radioactive isotopes can be created.
No, there are many stable isotopes.
Not all isotopes are radioactive; the radioactive isotopes are unstable and emit radiations.
Not all of the transition elements are radioactive. Many of them are, and some of them have common radioactive isotopes, but some of them have no naturally occurring radioactive isotopes. Please note that all elements have synthetic radioactive isotopes, at least.
Both isotopes and radioactive isotopes are pretty much the same but radioactive isotopes are better because it can be used to make medicine.
Today are known approx. 3 000 radioactive isotopes, natural or artificial.
2
All of them.
Sodium has no radioactive isotopes.
Radioactive isotopes are not stable.
All the uranium isotopes are radioactive.