d and f Block Elements Part 1

The exothermic hydration enthalpies of the given trivalent cations are:
Sc+3=3960kJ∕mole
Fe+3=4429kJ∕ mole
Co+3=4653kJ∕mole
Cr+3=4563kJ∕mole
Hence Sc+3 is least hydrated; so least stable (not most stable)
Fe+2 contains 4 unpaired electrons where as Mn+2 contains 5 unpaired electrons hence (4) is incorrect.