what are isotopes of Niobium ??

Answer 1

Naturally occurring niobium (Nb) is composed of one stable isotope (Nb-93). The most stable radioisotopes are Nb-92 with a half-life of 34.7 million years, Nb-94 (half life: 20300 years), and Nb-91 with a half life of 680 years. There is also a meta state at 31 keV whose half-life is 16.13 years. Twenty three other radioisotopes have been characterized. Most of these have half lives that are less than two hours except Nb-95 (35 days), Nb-96 (23.4 hours) and Nb-90 (14.6 hours). The primary decay mode before the stable Nb-93 is electron capture and the primary mode after is beta emission with some neutron emission occurring in the first mode of the two mode decay of Nb-104, 109 and 110.

Only Nb-95 (35 days) and Nb-97 (72 minutes) and heavier isotopes (halflives in seconds) are fission products in significant quantity, as the other isotopes are shadowed by stable or very long-lived (Zr-93) isotopes of the preceding element zirconium from production via beta decay of neutron-rich fission fragments. Nb-95 is the decay product of Zr-95 (64 days), so disappearance of Nb-95 in used nuclear fuel is slower than would be expected from its own 35 day halflife alone.. Tiny amounts of the other isotopes may be produced as direct fission products.
Standard atomic mass: 92.90638(2) u