Which of the following ligands is neutral?

$[EDTA]^{4-}$ is a:

Ammonia acts as a ligand but ammonium ion does not form complexes because

The coordination number of copper in cuprammonium sulphate is

The mass of carbon present in $0.5 \, mol$ of $K_4[Fe(CN)_6]$ is .............. $g$.

An octahedral complex with the formula $CoCl_3 \cdot nNH_3$ upon reaction with excess of $AgNO_3$ solution gives $2$ moles of $AgCl$. Consider the oxidation state of $Co$ in the complex is '$x$'. The value of $x+n$ is . . . . .