Which of the following ligands possesses only one coordination site?

Which of the following will not give a white precipitate with silver nitrate $(AgNO_3)$?

Which of the following complexes is heteroleptic?

What is the chemical formula of sodium nitroprusside?

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

Given the molecular formulas of the hexa-coordinated complexes: $(a)$ $CoCl_3 \cdot 6NH_3$,$(b)$ $CoCl_3 \cdot 5NH_3$,$(c)$ $CoCl_3 \cdot 4NH_3$. If the number of coordinated $NH_3$ molecules in $(a)$,$(b)$,and $(c)$ are $6, 5$,and $4$ respectively,the primary valencies in $(a)$,$(b)$,and $(c)$ are: