look at a Periodic Table :)
copper has 2 stable isotopes
No, there are many stable isotopes.
It has 10
Dubnium is an artificial chemical element and hasn't stable isotopes.
it has 3 stable isotopes
No, most isotopes are not stable. Many isotopes are radioactive and decay over time, releasing radiation in the process. Only a few isotopes are stable and do not undergo radioactive decay.
There is one stable isotope in Niobium, Nb93 there are 28 known isotopes in all.
Oxygen consists of three stable isotopes: 16O, 17O, and 18O
3
2
1
one