Which one of the following orders is correct for the bond dissociation enthalpy of halogen molecules?

Which one of the following orders is correct for the bond dissociation enthalpy of halogen molecules?
  1. I2>Br2>Cl2>F2
  2. Cl2>Br2>F2>I2
  3. Br2>I2>F2>Cl2
  4. F2>Cl2>Br2>I2

Solution

Decreasing order of Bond energy, Cl2>Br2>F2>I2

The reason is anomalous behavior due to large electron - electron repulsion among the lone pairs in F2 molecule other than Cl2 and Br2 .

Asked in: MHT CET Full Test 7

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