The primary valency of iron in ${\mathrm{K}}_4\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]$ is

All the following complexes show decrease in their weights when placed in a magnetic balance then the group of complexes having tetrahedral geometry is

$\left(\mathrm{I}\right)$ $\mathrm{Ni}(\mathrm{CO}{)}_4$

$\left(\mathrm{II}\right)$ $\mathrm{K}\left[{\mathrm{AgF}}_4\right]$

$\left(\mathrm{III}\right)$ ${\mathrm{Na}}_2\left[\mathrm{Zn}{\left(\mathrm{CN}\right)}_4\right]$

$\left(\mathrm{IV}\right)$${\mathrm{K}}_2\left[{\mathrm{PtCl}}_4\right]$

$\left(\mathrm{V}\right)$ $\left[RhCl{\left({\mathrm{PPh}}_3\right)}_3\right]$