Among the following the correct order of acidity is

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

Which of the statements given below is incorrect?

The formation of the oxide ion, O^2$$-$$_(g) from oxygen atom requires first an exthermic and then an endothermic step as shown below:
O_(g) + e^$$-$$ $$ \to $$ O^$$-$$_(g);  $$\Delta $$_fH^o = $$-$$141 kJ mol^$$-$$1

O^$$-$$_(g) + e^$$-$$ $$ \to $$ O^2$$-$$_(g);  $$\Delta $$_fH^o = +780 kJ mol^$$-$$1

Thus, process of formation of O^2$$-$$ is isoelectronic with neon. It is due to the fact that,