Which of the following metal ions forms a complex with $CN^-$ having a coordination number of $2$?

The number of chloride ions produced in an aqueous solution of tetraamminedichloroplatinum $(IV)$ chloride is ...........

Give the chemical formulas for the following:
$(i)$ Sodium nitroprusside
$(ii)$ The purple solution formed in the test for sulphur
$(iii)$ Sodium hexacyanoferrate $(II)$
$(iv)$ Iron $(III)$ hexacyanoferrate $(II)$
$(v)$ Ferri-ferrocyanide
$(vi)$ Sodium thiocyanate

$A$ complex compound of $Co^{3+}$ with molecular formula $CoCl_{x} \cdot yNH_3$ gives a total of $3$ ions when dissolved in water. How many $Cl^{-}$ ions satisfy both primary and secondary valencies in this complex?

The ligand $N[CH_2CH_2NH_2]_3$ is a:

Identify the cationic complex from the following.