In
Third electron which is removed to give third
ionisation potential, belongs to 3d3 subshell.
Third electron which is removed to give third
ionisation potential, belongs to 3d5 subshell.
Third electron which is removed to give third
ionisation potential, belongs to 3d6 subshell.
Third electron which is removed to give third
ionisation potential, belongs to 3d5 subshell.
In all elements shell and subshells are same.
Required amount of energy (enthalpy) is based upon the stability of d-subshell.
The -subshell has high stability in all because it is half-filled subshell. So, Mn shows highest third ionisation potential.