KEAM 2017 Physics and Chemistry Paper

For the species having same number of electrons, have same bond order.
Number of electrons for CO=6+8=14
Number of electrons for CN−=6+7+1=14
Number of electrons from NO+=7+8−1=14
Hence, all the given species are iso-electronic and have same bond-order (three)
Hence, option (a) is the correct answer.