Which of the following is a neutral ligand?

$2.33 \ g$ 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 : $Co = 59, Cl = 35.5, Ag = 108$]

How many $EDTA$ (ethylenediaminetetraacetic acid) molecules are required to make an octahedral complex with a $Ca^{2+}$ ion?

How many molecules of $EDTA$ (Ethylenediaminetetraacetic acid) are required to form an octahedral complex with a $Ca^{2+}$ ion?

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

Which of the following gives a white precipitate with $AgNO_3$?