Which of the following is isoelectronic pair?

1. ICl2 , ClO2 2. BrO2- , BrF2+
3. ClO2 , BrF 4. CN- , O3
 
 



Hint: Isoelectronic species have the same number of electrons. 

Isoelectronic pairs have the same number of electrons

BrO2- BrF2+

Total number of electrons

 35 + 2 × 8 + 1 = 52

 35 + 9 × 2 – 1 = 52

Hence,(b) is the correct choice, while in another case this value is not equal.

ICl2

ClO2

53 + 2 x 17 = 87

17 + 16 = 33

ClO2

BrF

17 + 16 = 33

35+ 9=44

CN-

O3

6 + 7 + 1 = 14

8 x 3 = 24

Hence, only (b) is the correct choice