isoelectronic molecules and ions have identical bond order .

How??

Bond order is find out by molecular orbital theory .In MOT electrons are filled in bonding and anti bonding orbitals . and then bond order is calculated by BO = no.of electrons in anti bonding orbitals ~ no.of electrons in bonding orbital / 2 So in I so electronic species no. Of electrons are same therefore same arrangement in bonding and anti bonding orbitals .and hence the bond order .