Question

Which of the following ion is paramagnetic?

• A. $C{u}^{+}$
• B. $Z{n}^{2+}$
• C. $O_2^{2-}$
• D. $C{r}^{3+}$

Answer 1

The correct option is D $C{r}^{3+}$

Ions with unpaired electron is paramagnetic. Elelctronic configuration and unpaired electron in the given ions are:

$C{u}^{+}:3d^{10}$: 0 unpaired electron

$Z{n}^{2+}:3d^{10}$: 0 unpaired electron

$O_2^{2-}:\sigma 2p^2\pi 2p^4{\pi }^{\ast }2p^4$: 0 unpaired electron

$C{r}^{3+}:3d^3$: 3 unpaired electron

thus option D is correct.