Structure of Atom — Chemistry STD 11 Science — Question

2. Fe³⁺, Mn²⁺.

Explanation:

Cr³⁺ (Z = 24) = [Ar]3d³

Fe³⁺ (Z = 26) = [Ar]3d⁵

Mn²⁺ (Z = 25) = [Ar]3d⁵

Co³⁺ (Z = 27) = [Ar]3d⁶

Sc³⁺ (Z = 21) = [Ar]3d⁰

Fe³⁺ and Mn²⁺ will have the same number of electrons, i.e., 23 and, hence, have the same electronic configuration.