Would you expect the second electron gain enthalpy of `O` as positive, more negative or less negative than the first? Justify your answer.

Explanation

The second electron gain enthalpy of oxygen would be positive. This is because after the addition of one electron, it becomes negatively charged. The second electron is added to negatively charged ion and the addition is opposed by coulombic repulsions, Therefore, energy has to be supplied to force the second electron into the anion and hence second electron gain enthalpy would be positive.