Which of the following is an example of a hexadentate ligand?

Which complex among the following gives a white precipitate on treatment with an aqueous solution of barium chloride?

$A$ coordination complex compound of cobalt has a molecular formula containing five ammonia molecules,one nitro group,and two chlorine atoms for one cobalt atom. One mole of this compound produces three moles of ions in an aqueous solution,and upon reacting with an excess of $AgNO_3$,it forms $AgCl$ precipitate. The ionic formula for this complex would be:

The number of neutral molecules or negative groups attached to the central metal atom in a complex ion is called:

The $NO$ molecule,

The coordination number of a central metal atom in a complex can be determined by $......$.