Chelating ligands among the following are:

(i) dien                            (ii) C₂O₄^3-

(iii) gly                             (iv) py

(v) dipy

i, ii, iii, v

The correct answer is option 2. i, ii, iii, v.

Let us break down each ligand to understand why it is or isn't chelating:

1. dien (diethylenetriamine):

Structure:

It has three nitrogen atoms, each with a lone pair that can coordinate to a metal ion. This makes dien a tridentate chelating ligand because it can form three bonds to a metal ion.

2. \(C_2O_4^{2-}\) (oxalate):

Structure:

It has two oxygen atoms, each with a lone pair that can coordinate to a metal ion. This makes oxalate a bidentate chelating ligand because it can form two bonds to a metal ion.

3. gly (glycine):

Structure:

It can act as a chelating ligand when it deprotonates to form \(NH_2-CH_2-COO^-\). In this form, it can coordinate to a metal ion through the nitrogen atom of the amine group and one oxygen atom of the carboxylate group. This makes glycine a bidentate chelating ligand.

4. py (pyridine):

Structure:

It has only one nitrogen atom with a lone pair that can coordinate to a metal ion. Since it has only one donor atom, it cannot form multiple bonds to a single metal ion. Therefore, pyridine is not a chelating ligand.

5. dipy (2,2'-bipyridine):

Structure:

It has two nitrogen atoms, each with a lone pair that can coordinate to a metal ion. This makes 2,2'-bipyridine a bidentate chelating ligand because it can form two bonds to a metal ion.

Therefore, the ligands dien, \(C_2O_4^{2-}\), glycine, and dipy are chelating ligands, while pyridine is not. Hence, the correct answer is: i, ii, iii, v