Which of the following ligands possesses only one coordination site?

$2.33 \ g$ of compound $X$ (empirical formula $= CoH_{12}N_{4}Cl_{3}$) upon treatment with excess $AgNO_{3}$ solution produces $1.435 \ g$ of a white precipitate. The primary and secondary valences of cobalt in compound $X$,respectively are.
[Given,atomic mass : $Co = 59, Cl = 35.5, Ag = 108$]

What is the coordination number of cobalt in $[Co(en)_2Br_2]Cl_2$?

Which of the following complexes gives a white precipitate with a solution of barium chloride $(BaCl_2)$?

$A$ coordination complex contains $Co^{3+}$,$Cl^{-}$,and $NH_3$. When dissolved in water,one mole of this complex gives a total of $3$ moles of ions. The complex is

$H_2N - CH_2 - CH_2 - NH_2$ acts as a: