Q.Among the following, the compound that contains ionic, covalent and co-ordinate linkage is

An ordinary covalent bond forms when both combining atoms each contribute one electron to the shared pair. A coordinate covalent bond (also called a dative or coordinate bond) is the special case where only ONE of the two atoms -- the donor -- supplies BOTH electrons of the bonding pair; the other atom, the acceptor, contributes none but still shares in the resulting bond. Because the origin of the electron pair is asymmetric, a coordinate bond is drawn as an ARROW running from the donor atom to the acceptor atom, rather than the plain line used for a normal covalent bond -- though once formed, a coordinate bond is otherwise indistinguishable in strength and behaviour from an ordinary covalent bond.

Example 1 — the ferrocyanide ion, [Fe(CN)₆]⁴⁻. Each of the six cyanide ions (CN⁻) has a lone pair (on carbon) available to donate; each donates its pair to the Fe²⁺ centre, forming six Fe-CN coordinate bonds. (This donor/acceptor language carries directly over into coordination chemistry, where the donor atom is called a ligand and the acceptor is the central metal ion.) …