The d-electron configuration of Cr 2+, Mn 2+, Fe 2+ and Co 2+ are d 4, d 5, d 6 and d 7 respectively. Which one of the following will exhibit minimum paramagnetic behaviour? [CBSE AIPMT 2007]

Magnetic moment= n n+2 Where n is number of unpaired electrons. So, the ion with minimum number of unpair electron will have minimum Paramagnetism Hence, [Co(H2O)6]2+ will exhibit minimum paramagnetic behavior as it has minimum number of number of unpaid electron.