An example of a double salt is:

Consider the following statements according to Werner's theory:
$1.$ Ligands are connected to the central metal ions by coordinate bonds.
$2.$ Secondary valencies have directional properties.
$3.$ Secondary valencies are non-ionisable.
Which of these statements are correct?

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

In dichlorodioxalatochromium$(III)$,the primary and secondary valencies are respectively ......

Which of the following represents a chelating ligand?

$A$ group of atoms can function as a ligand only when