Question

The number of unpaired electrons in gaseous species of $Mn^{3 +},Cr^{3 +}$and $V^{3 +}$ respectively are ____and the most stable species is _______

• A. 4, 2 and 2 ; $V^{3 +}$
• B. 3,3 and 2 ; $Cr^{3 +}$
• C. 4, 3 and 2 ; $Cr^{3 +}$
• D. 3,3 and 3; $Mn^{3 +}$

Answer 1

Answer: (C)

4, 3 and 2 ; $Cr^{3 +}$

Answer 2

$Mn^{3 +} = 3d^{4} = 4$unpaired electrons, $Cr^{3 +} = 3d^{3} = 3$ unpaired electrons, $V^{3 +} = 3d^{2} = 2$ unpaired electrons $Cr^{3 +}$is most stable out of these in aqueous solution because it has half filled $t_{2g}$ level (i.e. $t_{2g}^{3}$)