Question

The number of unpaired electrons in a chromic ion $C{r}^{+3}$ (atomic number 24) is:

• A. 6
• B. 4
• C. 3
• D. 1

Answer 1

The correct option is C 3

Atomic number of Cr = 24 & $C{r}^{3+}$ = 21.
E.C of $Cr$ = $\left[Ar\right]4s^{1}3d^5$
Therefore, E.C of $C{r}^{3+}$ = $\left[Ar\right]3d^3$.
No. of unpaired electrons = 3.