Answer: The elements that have 3 unpaired electrons in their +3 oxidation states are Molybdenum and Palladium.
Explanation: The elements in the second transition series are:
Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag) and Cadmium (Cd).
The electronic configuration of these elements are:
;
![Y^(3+)=[Kr]](https://img.qammunity.org/2018/formulas/chemistry/college/ujkvhzl7hunu2nmz0souwruv32eid3fv85.png)
;
![Zr^(3+)=[Kr]4d^1](https://img.qammunity.org/2018/formulas/chemistry/college/irqwfbwn3zgu0l4g8ekeqm4ftbg238u7oa.png)
;
![Nb^(3+)=[Kr]4d^2](https://img.qammunity.org/2018/formulas/chemistry/college/hna5t38n6d0dcuhlvps8u8pf9gtlajhium.png)
;
![Mo^(3+)=[Kr]4d^3](https://img.qammunity.org/2018/formulas/chemistry/college/tmn2icw4uf1fjfd6sjad83zbc0flcw1bwx.png)
;
![Tc^(3+)=[Kr]4ds^4](https://img.qammunity.org/2018/formulas/chemistry/college/8uyddls7z0wr0fhemhmld1hmmrt4vfb5wl.png)
;
;
![Rh^(3+)=[Kr]4d^6](https://img.qammunity.org/2018/formulas/chemistry/college/m3jdl972vsmfpb231h9qwckchwrjsy20fb.png)
;
![Pd^(3+)=[Kr]4d^7](https://img.qammunity.org/2018/formulas/chemistry/college/vjj1burt00pelky13b0dohtf3zmy24y8ru.png)
;
![Ag^(3+)=[Kr]4d^8](https://img.qammunity.org/2018/formulas/chemistry/college/i1xhd6vftn7a4b3reyikamv4hgaos6jp3k.png)
;
![Cd^(3+)=[Kr]4d^9](https://img.qammunity.org/2018/formulas/chemistry/college/4jsgixsmpmg1srqxsggk6o3ql9l0o0r6zf.png)
From the above configurations of the elements in their +3 ionic state, the elements having 3 unpaired electrons are Molybdenum and Palladium.