The pair of ions having same electronic configuration is:

• The electronic configurations of Cr⁺³ and Fe⁺³are,

Cr(Z=24), [Ar]3d⁵4s¹ and Cr⁺³has [Ar]3d³

Fe(Z=26),[Ar]3d⁶4s² and Fe³⁺ has [Ar]3d⁵

Thus, Cr⁺³ and Fe⁺³ have different electronic configuration.

• The electronic configurations of Fe⁺³ and Mn²⁺ are,

Fe(Z=26),[Ar]3d⁶4s² and Fe³⁺ has [Ar]3d⁵

Mn(Z=25),[Ar]3d⁵4s² and Mn²⁺ has [Ar]3d⁵

Thus, Fe⁺³ and  Mn²⁺ have similar electronic configuration.

• The electronic configurations of Fe+3 and Co3+ are,

Fe(Z=26),[Ar]3d⁶4s² and Fe³⁺ has [Ar]3d⁵

Co(Z=27),[Ar]3d⁷4s² now, Co³⁺ has [Ar]3d⁶

Thus, Fe⁺³ and Co⁺³ have different electronic configuration.

• The electronic configurations of Cr⁺³ and Sc³⁺are,

Cr(Z=24)=[Ar]3d⁵4s¹ now, Cr³⁺ has [Ar]3d³

Sc(Z=21)=[Ar]3d¹4s² and Sc³⁺has [Ar]3d⁰

Thus, Cr⁺³ and Sc³⁺ have different electronic configuration.