Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionisation enthalpy ?

Step-by-step solution

V 2 + (21) [ Ar ] 18 3d 3 4s 0 Cr 2 + (22) [ Ar ] 18 3d 4 4s 0 Mn 2 + (23) [ Ar ] 18 3d 5 4s 0 Fe 2 + (24) [ Ar ] 18 3d 5 4s 1 To find ionization enthalpy we first see electronic configuration. Then we see shell. If shell are same then see charge. Then see extra stability ( Half filled and fully filled ). ⇒ I.E 3 Mn > I.E 3 Fe > I.E 3 Cr > I.E 3 V