Which of the following is isoelectronic pair?
ISOELECTRONIC SPECIES: the ions or elements which have same number of electrons are called isoelectronic species.
Number of electrons in the given species;
ICl2 : 53 + 2*17 = 87
ClO2 ; 17 + 16 = 33
Therefore number of electrons is not same. Hence it cannot be isoelectronic pair.
BrO2 : 35 + 2*8 + 1 = 52
BrF2: 35 + 9*2 -1 = 52
Therefore number of electrons is same. Hence it is a isoelectronic pair.
ClO2 : 17 + 16 = 33
BrF : 35 + 9 = 44
Therefore number of electrons is not same. Hence it cannot be isoelectronic pair.
CN- : 6+7+1 = 14
O3 : 8*3 = 24
Therefore number of electrons is not same. Hence it cannot be isoelectronic pair.
Hence the correct option is (ii).