Question

Select Paramagnetic molecule :
(A) ${KO}_2$
(B) $cis-{\left[Co{\left(en\right)}_{2}C{l}_2\right]}^{+}$
(C) $K_3\left[Co{\left(Ox\right)}_3\right]$
(D) ${\left[Co{Cl}_3\right]}^{2-}$

• A. A, B, C
• B. A, D
• C. B, C, D
• D. A, C, D

Answer 1

The correct option is B A, D

$K{O}_2$ is a paramagnetic molecule as it is a superoxide having $O_2^{-}$ ion. In (b) & (c), $C{o}^{3+}$ is present containing $6$ $d$ electrons. However all these electrons are paired up due to presence of strong field ligands. $\left(d\right)$ has $C{o}^{2+}$ ions with $7d$ electrons, out of which $3$ are unpaired due to presence of weak field ligand $Cl$.

Hence $K{O}_2$ and $[CoC{l}_3{]}^{2-}$ are paramagnetic molecules .