Q. The d-electron configurations of Cr2 , Mn2 , Fe2 and Co2 are d4, d5, d6 and d7 respectively. Which one of the following will exhibit minimum paramagnetic behaviour?(At. nos. Cr = 24, Mn = 25, Fe = 26, Co = 27)

1. [Co(H2O)6]2+
2. [Fe(H2O)6]2+
3. [Mn(H2O)6]2+
4. [Cr(H2O)6]2+