Find the number of chemical species among following that have dπ - pπ bonds in their structure
NO3−, SO3, XeO3, H3PO4, ClO4−, CO32−, SO42−, (CN)2, XeOF2
SO3, XeO3, H3PO4, ClO4−, SO42−, XeOF2 have dp - pp bonding.