Question

what is a ligand and what are the various types of ligands?

Answer 1

ligands are the elements which have a pair of electron to donate the electron
Types of Ligands

Unidentate ligands: Ligands with only one donor atom, e.g. NH3, Cl-, F- etc.

Bidentate ligands: Ligands with two donor atoms, e.g. ethylenediamine, C2O42-(oxalate ion) etc. 

Tridentate ligands: Ligands which have three donor atoms per ligand, e.g. (dien) diethyl triamine.

Hexadentate ligands: Ligands which have six donor atoms per ligand, e.g. EDTA. 

Chelating Ligands: Multidentate ligand simultaneously co-ordinating to a metal ion through more than one site is called chelating ligand. These ligands produce a ring like structure called chelate. Chelation increases the stability of complex. This effect is called chelation effect.