PSEUDO HALOGENS ARE UNIVALENT IONS CONSISTING OF TWO OR MORE ATOMS OF WHICH ATLEAST ONE IS NITROGEN AND HAVE PROPERTIES SIMILAR TO HALOGEN. FOR EG.
anions : CN- , SCN- , NCN-2
acids : HCN, HSCN, H2NCN
dimer : (CN)2 , (SCN)2
*** CN- shows maximum similarities with hallides