Question
Which one of the following orders is correct for the bond dissociation enthalpy of halogen molecules?
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Cl2>Br2>F2>I2
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Br2>I2>F2>Cl2
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F2>Cl2>Br2>I2
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I2 >Br2>Cl2>F2
Solution
A.
Cl2>Br2>F2>I2
Bond dissociation energies of halogen family decrease down the group as the size of the atom increases. The bond dissociation energy of fluorine, is, however, lower than those of chlorine and bromine because of interelectronic repulsions present in the small atom of fluorine.
Hence bond energy decreases in the order Cl2 > Br2 > F2 > I2
