NEET2016ChemistryClassification of Elements and Periodicity in PropertiesActual
Which one of the following orders is correct for the bond dissociation enthalpy of halogen molecules?
Options
- AI 2 > B r 2 > C l 2 > F 2
- BC l 2 > B r 2 > F 2 > I 2
- CB r 2 > I 2 > F 2 > C l 2
- DF 2 > C l 2 > B r 2 > I 2
Correct answer
B. C l 2 > B r 2 > F 2 > I 2
Step-by-step solution
Decreasing order of Bond energy, C l 2 > B r 2 > F 2 > I 2 The reason is anomalous behavior due to large electron - electron repulsion among the lone pairs in F 2 molecule other than C l 2 and B r 2 .