Chemistry - Carbonyl compounds Question with Solution | TestHub

Odd electrons, ions and molecules are paramagnetic.
In$\mathrm{C}\mathrm{r}(\mathrm{C}\mathrm{O}{)}_6$molecule 12 electrons are contributed by –CO group and it contains no odd electron
$\mathrm{C}\mathrm{r}\to 3{\mathrm{d}}^{5}4{\mathrm{s}}^1$
$\mathrm{F}\mathrm{e}(\mathrm{C}\mathrm{O}{)}_5$molecule also does not contain odd electron.
$\mathrm{F}\mathrm{e}\to 3{\mathrm{d}}^{6}4{\mathrm{s}}^2$
In$\left[\mathrm{F}\mathrm{e}\right(\mathrm{C}\mathrm{N}{)}_6{]}^{4-}$ion$\mathrm{F}\mathrm{e}\left(+\mathrm{I}\mathrm{I}\right)$$\to 3{\mathrm{d}}^{6}4{\mathrm{s}}^0$
$\mathrm{S}\mathrm{o}$, no odd electrons
In$\left[\mathrm{C}\mathrm{r}\right(\mathrm{N}{\mathrm{H}}_3{)}_6{]}^{3+}$ion$\mathrm{C}\mathrm{r}(+\mathrm{I}\mathrm{I}\mathrm{I})$$\to 3{\mathrm{d}}^{3}4{\mathrm{s}}^0$
This iron contains odd electron so it is paramagnetic.