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

Options

A. Vanadium (Z = 23)
B. Chromium (Z = 24)
C. Manganese (Z = 25)
D. Iron (Z = 26).

Answer

C

Explanation

(c) The electronic configuration of divalent cation is :
`V^(2+)(Z=23),[Ar]3d^(3)`
`Cr^(2+)(Z=24),[Ar]3d^(4)`
`Mn^(2+)(Z=25),[Ar]3d^(5)`
`Fe^(2+)(Z=26),[Ar]3d^(6)`
Since the electronic configuration of `Mn^(2+)` is the most symmetrical, it has the highest third ionisation enthalpy.