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://tex.z-dn.net/?f=Y%5E%7B3%2B%7D%3D%5BKr%5D)
; ![Zr^{3+}=[Kr]4d^1](https://tex.z-dn.net/?f=Zr%5E%7B3%2B%7D%3D%5BKr%5D4d%5E1)
; ![Nb^{3+}=[Kr]4d^2](https://tex.z-dn.net/?f=Nb%5E%7B3%2B%7D%3D%5BKr%5D4d%5E2)
; ![Mo^{3+}=[Kr]4d^3](https://tex.z-dn.net/?f=Mo%5E%7B3%2B%7D%3D%5BKr%5D4d%5E3)
; ![Tc^{3+}=[Kr]4ds^4](https://tex.z-dn.net/?f=Tc%5E%7B3%2B%7D%3D%5BKr%5D4ds%5E4)
;
; ![Rh^{3+}=[Kr]4d^6](https://tex.z-dn.net/?f=Rh%5E%7B3%2B%7D%3D%5BKr%5D4d%5E6)
; ![Pd^{3+}=[Kr]4d^7](https://tex.z-dn.net/?f=Pd%5E%7B3%2B%7D%3D%5BKr%5D4d%5E7)
; ![Ag^{3+}=[Kr]4d^8](https://tex.z-dn.net/?f=Ag%5E%7B3%2B%7D%3D%5BKr%5D4d%5E8)
; ![Cd^{3+}=[Kr]4d^9](https://tex.z-dn.net/?f=Cd%5E%7B3%2B%7D%3D%5BKr%5D4d%5E9)
From the above configurations of the elements in their +3 ionic state, the elements having 3 unpaired electrons are Molybdenum and Palladium.