Define the following and give one example(a) Polydentate ligandOR(b) Homoleptic complex

(a) Polydentate ligand: A polydentate ligand is a type of ligand that has multiple donor atoms capable of forming coordination bonds with a central metal ion. These donor atoms are typically coordinated to the metal ion through their lone pairs of electrons. The number of donor atoms in a polydentate ligand is indicated by a prefix, such as "bi-" for two donor atoms or "tri-" for three donor atoms.

Example: Ethylenediamine (en) is a common polydentate ligand that has two nitrogen atoms capable of forming coordination bonds with a metal ion.

(b) Homoleptic complex: A homoleptic complex is a type of coordination complex in which all the ligands surrounding a central metal ion are the same. In other words, all the coordination sites of the metal ion are occupied by identical ligands.

Example: [Ni(CO)4] is a homoleptic complex in which all the coordination sites of the nickel ion are occupied by carbon monoxide ligands.