Which of the following bonds has the lowest bond enthalpy?

Options

A. `O-O`
B. `N-N`
C. `H-H`
D. `C-C`

Answer

A

Explanation

Bond enthalpy decreases as the bond length increases. On account of repulsion between lone pairs on adjacent atoms, the bond length decreases. There are no lone pairs on H and C atoms. N atoms have one lone pairs each while O atoms have two lone pairs each. Thus, inter-electronic repulsion is the maximum in `-overset(..)underset(..)O-overset(..)underset(..)O-` bond resulting in the weakest bond.