Element ' X ' is forming a complex of the type [XCl(H2O)5]2+. Total number of ligands attached to X is 6 (one Cl and five H2O ). ∴ Covalency of X is 6 . Cl is a unidentate ligand with charge −1. H2O is a unidentate ligand with charge 0 . ∴‌‌x+(−1)+0‌=+2 x−1‌=+2 x=+2+1=‌+3 ∴ Oxidation state of x is +3.