Verified Solution • 2025–26 Session
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QJEEM20Ch446a: JEE Main 2020 Chemistry - Class 11 JEEM20Ch446a Solution: The third ionization enthalpy is minimum for :
The third ionization enthalpy is minimum for :
Multiple Choice Options
- A Ni
- B Co
- C Mn
- D Fe
Step-by-Step Verified Solution
Electronic configuration of
25Mn = [Ar]3d54s2
25Mn2+ = [Ar]3d54s0
26Fe = [Ar]3d64s2
26Fe2+ = [Ar]3d64s0
27Co = [Ar]3d74s2
27Co2+ = [Ar]3d74s0
28Ni = [Ar]3d84s2
28Ni2+ = [Ar]3d84s0
So third ionisation energy is minimum for Fe.
25Mn = [Ar]3d54s2
25Mn2+ = [Ar]3d54s0
26Fe = [Ar]3d64s2
26Fe2+ = [Ar]3d64s0
27Co = [Ar]3d74s2
27Co2+ = [Ar]3d74s0
28Ni = [Ar]3d84s2
28Ni2+ = [Ar]3d84s0
So third ionisation energy is minimum for Fe.