Arrange the following transition metal ions in the increasing order of their number of unpaired electrons. (A) Ti ³⁺ (B) Ni ²⁺ (C) Cr ³⁺ (D) Fe ²⁺ (E) Mn ²⁺ Choose the correct answer from the options given below:

Step-by-step solution

The number of unpaired electrons in a transition metal ion is determined by writing its electronic configuration. Electrons are first removed from the outermost 4 s orbital, followed by the 3 d orbital. Ti ³⁺ (Z=22): Neutral Ti is [ Ar ] 4 s ^2 3 d ^2 . Removing 3 electrons gives [ Ar ] 3 d ^1 . (1 unpaired electron) Ni ²⁺ (Z=28): Neutral Ni is [ Ar ] 4 s ^2 3 d ^8 . Removing 2 electrons gives [ Ar ] 3 d ^8 . (2 unpaired electrons) Cr ³⁺ (Z=24): Neutral Cr is [ Ar ] 4 s ^1 3 d ^5 . Removing 3 electrons gives [ Ar ]